register interest

Professor Persephone Borrow

Research Area: Immunology
Technology Exchange: Cell sorting, Cellular immunology and Flow cytometry
Scientific Themes: Immunology & Infectious Disease
Keywords: human immunodeficiency virus, innate response, immune response, protective immunity, CD8+ T cell and CD4+ T follicular helper cell
Web Links:
Kinetics of the earliest innate and adaptive responses in acute HIV-1 infection
Nat. Rev. Immunol. 10: 11, 2010

Kinetics of the earliest innate and adaptive responses in acute HIV-1 infection Nat. Rev. Immunol. ...

The systemic cytokine storm induced in acute HIV-1 infection
J. Virol. 83: 3719, 2009

The systemic cytokine storm induced in acute HIV-1 infection J. Virol. 83: 3719, 2009

There is an urgent need for vaccines to combat infection with human immunodeficiency virus type 1 (HIV-1), persistent infection with which is associated with development of an acquired immunodeficiency syndrome (AIDS) currently responsible for ~3 million deaths per year worldwide. The key goals of prophylactic HIV vaccine strategies are to try to block the establishment of infection via induction of broadly-neutralising antibody (bNAb)  responses, and to induce rapidly-acting immune responses able to modulate the events in early infection that are now known to be critical determinants of the subsequent disease course: establishment, local expansion and dissemination of infection, exponential acute viral replication (resulting in depletion of the memory CD4+ T cell pool), followed by partial containment of viral replication and establishment of a setpoint persisting viral load. The major roadblocks currently hampering rational HIV vaccine design are the lack of understanding of how to elicit HIV-1 bNAbs; and the need to define the component(s) of an immune response able to intervene and mediate protection during the critical initial stages of infection.

One series of projects in the group aim to facilitate the development of vaccination strategies capable of eliciting HIV-1 bNAbs via induction of CD4 T cell responses that provide optimal help for the development of appropriate B cell responses. The relationship between the nature and specificity of the CD4 T cell response and development of bNAbs targeting particular viral epitopes in HIV-infected individuals is being explored; and the relative ability of different vaccination platforms to elicit CD4 T follicular helper cell responses is being determined.

Innate responses can be activated very rapidly in response to pathogen exposure or infection, and play important roles both in containment of early pathogen replication and promotion of induction of the adaptive response. In acute HIV infection, innate immune responses may also mediate immunopathological effects by driving immune activation and facilitating virus replication and spread. We thus hypothesise that the nature of the innate response in acute HIV-1 infection may be among the factors involved in determining the prognostically important setpoint viral load; and that aspects of innate responses may contribute to the resistance exhibited by certain individuals to full, seropositive HIV infection despite repeated viral exposure. A key implication of this is that modulation of innate responses could represent a novel approach to complement existing HIV vaccine strategies. A second series of projects in the group are addressing these hypotheses, focusing in particular on the role of type 1 interferons and other innate cytokines in blocking HIV-1 replication early after transmission, and the contribution of natural killer cells to HIV-1 control. We are also carrying out some comparative analysis of innate responses in the acute phase of other virus infections.

T cell responses play a key role in the elimination of many established virus infections, and multiple lines of evidence suggest that virus-specific CD8+ T cells make an important contribution to both the initial containment of primary viraemia and subsequent control of ongoing viral replication during HIV infection. Prophylactic and therapeutic strategies to combat HIV infection are thus also being designed to invoke this arm of the immune response. However the primary HIV-specific CD8 T cell response remains relatively poorly characterised, and how aspects of this response and its subsequent maintenance or evolution may impact on the initial and longer-term efficiency of control of virus replication are not well understood. A third series of projects within the group are analysing the relationship between qualitative aspects of the virus-specific CD8+ T cell response induced in primary HIV infection, the extent and kinetics of viral mutational escape from CD8+ T cell control, the fitness of the founder virus and its reduction as a consequence of acquisition of T cell escape mutations, and the subsequent efficiency of control of viral replication. We are also addressing the possibility that unconventional CD8+ T cell responses targeting novel HIV-1 epitopes could be employed to enhance vaccine-mediated HIV-1 control. 

 

Name Department Institution Country
Professor Mary Carrington National Cancer Institute United States
Prof Alexander (Hal) Drakesmith (RDM) Investigative Medicine Division Oxford University, Weatherall Institute of Molecular Medicine United Kingdom
Professor Simon J Draper Jenner Institute Oxford University, Old Road Campus Research Building United Kingdom
Professor Mike Dustin Kennedy Institute, University of Oxford United Kingdom
Professor Beatrice Hahn UPenn United States
Professor Barton Haynes Duke University, North Carolina United States
Professor Benedikt M Kessler Target Discovery Institute Oxford University, NDM Research Building United Kingdom
Professor Bette Korber Los Alamos National Laboratory United States
Professor Mala Maini UCL United Kingdom
Professor Sir Andrew J McMichael NDM Research Building Oxford University, NDM Research Building United Kingdom
Professor Stuart Neil Kings College London United Kingdom
Prof Graham Ogg (RDM) Investigative Medicine Division Oxford University, Weatherall Institute of Molecular Medicine United Kingdom
Professor Louis Picker Oregon Health and Sciences University United States
Prof Jan Rehwinkel (RDM) Investigative Medicine Division Oxford University, Weatherall Institute of Molecular Medicine United Kingdom
Professor George Shaw University of Pennsylvania United States
Professor Masafumi Takiguchi Kumamoto University Japan
Dr Ian Williams Royal Free and University College London United Kingdom
Benkirane M, Berkhout B, Borrow P, Fassati A, Fujii M, Garcia JV, Gorry P, Lever A, Mak J, Nijhuis M et al. 2017. Professor Mark Wainberg. Retrovirology, 14 (1), pp. 30. | Read more

Hassan AS, Hare J, Kamini G, Yindom LM, Kamali A, Karita E, Kilemba W, Price MA, Borrow P, Bjorkman P et al. 2017. A35 Viral evolution and innate immune responses during acute HIV-1 infection and their association with disease pathogenesis. Virus Evol, 3 (Suppl 1), | Read more

Borrow P, Moody MA. 2017. Immunologic characteristics of HIV-infected individuals who make broadly neutralizing antibodies. Immunol Rev, 275 (1), pp. 62-78. | Show Abstract | Read more

Induction of broadly neutralizing antibodies (bnAbs) capable of inhibiting infection with diverse variants of human immunodeficiency virus type 1 (HIV-1) is a key, as-yet-unachieved goal of prophylactic HIV-1 vaccine strategies. However, some HIV-infected individuals develop bnAbs after approximately 2-4 years of infection, enabling analysis of features of these antibodies and the immunological environment that enables their induction. Distinct subsets of CD4(+) T cells play opposing roles in the regulation of humoral responses: T follicular helper (Tfh) cells support germinal center formation and provide help for affinity maturation and the development of memory B cells and plasma cells, while regulatory CD4(+) (Treg) cells including T follicular regulatory (Tfr) cells inhibit the germinal center reaction to limit autoantibody production. BnAbs exhibit high somatic mutation frequencies, long third heavy-chain complementarity determining regions, and/or autoreactivity, suggesting that bnAb generation is likely to be highly dependent on the activity of CD4(+) Tfh cells, and may be constrained by host tolerance controls. This review discusses what is known about the immunological environment during HIV-1 infection, in particular alterations in CD4(+) Tfh, Treg, and Tfr populations and autoantibody generation, and how this is related to bnAb development, and considers the implications for HIV-1 vaccine design.

Iyer SS, Bibollet-Ruche F, Sherrill-Mix S, Learn GH, Plenderleith L, Smith AG, Barbian HJ, Russell RM, Gondim MV, Bahari CY et al. 2017. Resistance to type 1 interferons is a major determinant of HIV-1 transmission fitness. Proc Natl Acad Sci U S A, 114 (4), pp. E590-E599. | Show Abstract | Read more

Sexual transmission of HIV-1 is an inefficient process, with only one or few variants of the donor quasispecies establishing the new infection. A critical, and as yet unresolved, question is whether the mucosal bottleneck selects for viruses with increased transmission fitness. Here, we characterized 300 limiting dilution-derived virus isolates from the plasma, and in some instances genital secretions, of eight HIV-1 donor and recipient pairs. Although there were no differences in the amount of virion-associated envelope glycoprotein, recipient isolates were on average threefold more infectious (P = 0.0001), replicated to 1.4-fold higher titers (P = 0.004), were released from infected cells 4.2-fold more efficiently (P < 0.00001), and were significantly more resistant to type I IFNs than the corresponding donor isolates. Remarkably, transmitted viruses exhibited 7.8-fold higher IFNα2 (P < 0.00001) and 39-fold higher IFNβ (P < 0.00001) half-maximal inhibitory concentrations (IC50) than did donor isolates, and their odds of replicating in CD4(+) T cells at the highest IFNα2 and IFNβ doses were 35-fold (P < 0.00001) and 250-fold (P < 0.00001) greater, respectively. Interestingly, pretreatment of CD4(+) T cells with IFNβ, but not IFNα2, selected donor plasma isolates that exhibited a transmitted virus-like phenotype, and such viruses were also detected in the donor genital tract. These data indicate that transmitted viruses are phenotypically distinct, and that increased IFN resistance represents their most distinguishing property. Thus, the mucosal bottleneck selects for viruses that are able to replicate and spread efficiently in the face of a potent innate immune response.

Keating SM, Heitman JW, Wu S, Deng X, Stacey AR, Zahn RC, de la Rosa M, Finstad SL, Lifson JD, Piatak M et al. 2016. Magnitude and Quality of Cytokine and Chemokine Storm during Acute Infection Distinguish Nonprogressive and Progressive Simian Immunodeficiency Virus Infections of Nonhuman Primates. J Virol, 90 (22), pp. 10339-10350. | Show Abstract | Read more

Acute human immunodeficiency virus (HIV) infection represents a period of intense immune perturbation and activation of the host immune system. Study of the eclipse and viral expansion phases of infection is difficult in humans, but studies in nonprogressive and progressive nonhuman primate (NHP) infection models can provide significant insight into critical events occurring during this time. Cytokines, chemokines, and other soluble immune factors were measured in longitudinal samples from rhesus macaques infected with either SIVmac251 (progressive infection) or SIVmac239Δnef (attenuated/nonprogressive infection) and from African green monkeys infected with SIVsab9315BR (nonpathogenic infection). Levels of acute-phase peak viral replication were highest in SIVmac251 infection but correlated positively with viremia at 3 months postinfection in all three infection models. SIVmac251 infection was associated with stronger corresponding acute-phase cytokine/chemokine responses than the nonprogressive infections. The production of interleukin 15 (IL-15), IL-18, gamma interferon (IFN-γ), granulocyte colony-stimulating factor (G-CSF), monocyte chemoattractant protein 1 (MCP-1), macrophage inflammatory protein 1β (MIP-1β), and serum amyloid A protein (SAA) during acute SIVmac251 infection, but not during SIVmac239Δnef or SIVsab9315BR infection, correlated positively with chronic viremia at 3 months postinfection. Acute-phase production of MCP-1 correlated with viremia at 3 months postinfection in both nonprogressive infections. Finally, a positive correlation between the acute-phase area under the curve (AUC) for IL-6 and soluble CD40 ligand (sCD40L) and chronic viremia was observed only for the nonprogressive infection models. While we observed dynamic acute inflammatory immune responses in both progressive and nonprogressive SIV infections, the responses in the nonprogressive infections were not only lower in magnitude but also qualitatively different biomarkers of disease progression. IMPORTANCE: NHP models of HIV infection constitute a powerful tool with which to study viral pathogenesis in order to gain critical information for a better understanding of HIV infection in humans. Here we studied progressive and nonprogressive simian immunodeficiency virus (SIV) infection models in both natural and nonnatural host NHP species. Regardless of the pathogenicity of the virus infection and regardless of the NHP species studied, the magnitude of viremia, as measured by area under the curve, during the first 4 weeks of infection correlated positively with viremia in chronic infection. The magnitude of cytokine and chemokine responses during primary infection also correlated positively with both acute-phase and chronic viremia. However, the pattern and levels of specific cytokines and chemokines produced differed between nonprogressive and progressive SIV infection models. The qualitative differences in the early immune response in pathogenic and nonpathogenic infections identified here may be important determinants of the subsequent disease course.

Foster TL, Wilson H, Iyer SS, Coss K, Doores K, Smith S, Kellam P, Finzi A, Borrow P, Hahn BH, Neil SJD. 2016. Resistance of Transmitted Founder HIV-1 to IFITM-Mediated Restriction. Cell Host Microbe, 20 (4), pp. 429-442. | Show Abstract | Read more

Interferon-induced transmembrane proteins (IFITMs) restrict the entry of diverse enveloped viruses through incompletely understood mechanisms. While IFITMs are reported to inhibit HIV-1, their in vivo relevance is unclear. We show that IFITM sensitivity of HIV-1 strains is determined by the co-receptor usage of the viral envelope glycoproteins as well as IFITM subcellular localization within the target cell. Importantly, we find that transmitted founder HIV-1, which establishes de novo infections, is uniquely resistant to the antiviral activity of IFITMs. However, viral sensitivity to IFITMs, particularly IFITM2 and IFITM3, increases over the first 6 months of infection, primarily as a result of neutralizing antibody escape mutations. Additionally, the ability to evade IFITM restriction contributes to the different interferon sensitivities of transmitted founder and chronic viruses. Together, these data indicate that IFITMs constitute an important barrier to HIV-1 transmission and that escape from adaptive immune responses exposes the virus to antiviral restriction.

Wang C, Hart M, Chui C, Ajuogu A, Brian IJ, de Cassan SC, Borrow P, Draper SJ, Douglas AD. 2016. Germinal Center B Cell and T Follicular Helper Cell Responses to Viral Vector and Protein-in-Adjuvant Vaccines. J Immunol, 197 (4), pp. 1242-1251. | Show Abstract | Read more

There is great interest in the development of Ab-inducing subunit vaccines targeting infections, including HIV, malaria, and Ebola. We previously reported that adenovirus vectored vaccines are potent in priming Ab responses, but uncertainty remains regarding the optimal approach for induction of humoral immune responses. In this study, using OVA as a model Ag, we assessed the magnitude of the primary and anamnestic Ag-specific IgG responses of mice to four clinically relevant vaccine formulations: replication-deficient adenovirus; modified vaccinia Ankara (a poxvirus); protein with alum; and protein in the squalene oil-in-water adjuvant Addavax. We then used flow cytometric assays capable of measuring total and Ag-specific germinal center (GC) B cell and follicular Th cell responses to compare the induction of these responses by the different formulations. We report that adenovirus vectored vaccines induce Ag insert-specific GC B cell and Ab responses of a magnitude comparable to those induced by a potent protein/squalene oil-in-water formulation whereas-despite a robust overall GC response-the insert-specific GC B cell and Ab responses induced by modified vaccinia Ankara were extremely weak. Ag-specific follicular Th cell responses to adenovirus vectored vaccines exceeded those induced by other platforms at day 7 after immunization. We found little evidence that innate immune activation by adenovirus may act as an adjuvant in such a manner that the humoral response to a recombinant protein may be enhanced by coadministering with an adenovirus lacking a transgene of interest. Overall, these studies provide further support for the use of replication-deficient adenoviruses to induce humoral responses.

Moody MA, Pedroza-Pacheco I, Vandergrift NA, Chui C, Lloyd KE, Parks R, Soderberg KA, Ogbe AT, Cohen MS, Liao HX et al. 2016. Immune perturbations in HIV-1-infected individuals who make broadly neutralizing antibodies. Sci Immunol, 1 (1), pp. aag0851. | Show Abstract | Read more

Induction of broadly neutralizing antibodies (bnAbs) is a goal of HIV-1 vaccine development. bnAbs occur in some HIV-1-infected individuals and frequently have characteristics of autoantibodies. We have studied cohorts of HIV-1-infected individuals who made bnAbs and compared them with those who did not do so, and determined immune traits associated with the ability to produce bnAbs. HIV-1-infected individuals with bnAbs had a higher frequency of blood autoantibodies, a lower frequency of regulatory CD4(+) T cells, a higher frequency of circulating memory T follicular helper CD4(+) cells, and a higher T regulatory cell level of programmed cell death-1 expression compared with HIV-1-infected individuals without bnAbs. Thus, induction of HIV-1 bnAbs may require vaccination regimens that transiently mimic immunologic perturbations in HIV-1-infected individuals.

Haynes BF, Shaw GM, Korber B, Kelsoe G, Sodroski J, Hahn BH, Borrow P, McMichael AJ. 2016. HIV-Host Interactions: Implications for Vaccine Design. Cell Host Microbe, 19 (3), pp. 292-303. | Show Abstract | Read more

Development of an effective AIDS vaccine is a global priority. However, the extreme diversity of HIV type 1 (HIV-1), which is a consequence of its propensity to mutate to escape immune responses, along with host factors that prevent the elicitation of protective immune responses, continue to hinder vaccine development. Breakthroughs in understanding of the biology of the transmitted virus, the structure and nature of its envelope trimer, vaccine-induced CD8 T cell control in primates, and host control of broadly neutralizing antibody elicitation have given rise to new vaccine strategies. Despite this promise, emerging data from preclinical trials reinforce the need for additional insight into virus-host biology in order to facilitate the development of a successful vaccine.

Keating SM, Heitman JW, Wu S, Deng X, Stacey AR, Zahn RC, de la Rosa M, Finstad SL, Lifson JD, Piatak M et al. 2016. Magnitude and quality of cytokine and chemokine storm during acute infection distinguish nonprogressive and progressive simian immunodeficiency virus infections of nonhuman primates Journal of Virology, 90 (22), pp. 10339-10350. | Show Abstract | Read more

© 2016, American Society for Microbiology. All Rights Reserved. Acute human immunodeficiency virus (HIV) infection represents a period of intense immune perturbation and activation of the host immune system. Study of the eclipse and viral expansion phases of infection is difficult in humans, but studies in nonprogressive and progressive nonhuman primate (NHP) infection models can provide significant insight into critical events occurring during this time. Cytokines, chemokines, and other soluble immune factors were measured in longitudinal samples from rhesus macaques infected with either SIVmac251 (progressive infection) or SIVmac239Δnef (attenuated/nonprogressive infection) and from African green monkeys infected with SIVsab9315BR (nonpathogenic infection). Levels of acute-phase peak viral replication were highest in SIVmac251 infection but correlated positively with viremia at 3 months postinfection in all three infection models. SIVmac251 infection was associated with stronger corresponding acute-phase cytokine/chemokine responses than the nonprogressive infections. The production of interleukin 15 (IL-15), IL-18, gamma interferon (IFN-γ), granulocyte colony- stimulating factor (G-CSF), monocyte chemoattractant protein 1 (MCP-1), macrophage inflammatory protein 1β (MIP- 1β), and serum amyloid A protein (SAA) during acute SIVmac251 infection, but not during SIVmac239Δnef or SIVsab9315BR infection, correlated positively with chronic viremia at 3 months postinfection. Acute-phase production of MCP-1 correlated with vire mia at 3 months postinfection in both nonprogressive infections. Finally, a positive correlation between the acute-phase area under the curve (AUC) for IL-6 and soluble CD40 ligand (sCD40L) and chronic viremia was observed only for the nonprogressive infection models. While we observed dynamic acute inflammatory immune responses in both progressive and nonprogressive SIV infections, the responses in the nonprogressive infections were not only lower in magnitude but also qualitatively different biomarkers of disease progression.

Ternette N, Yang H, Partridge T, Llano A, Cedeño S, Fischer R, Charles PD, Dudek NL, Mothe B, Crespo M et al. 2016. Defining the HLA class I-associated viral antigen repertoire from HIV-1-infected human cells. Eur J Immunol, 46 (1), pp. 60-69. | Show Abstract | Read more

Recognition and eradication of infected cells by cytotoxic T lymphocytes is a key defense mechanism against intracellular pathogens. High-throughput definition of HLA class I-associated immunopeptidomes by mass spectrometry is an increasingly important analytical tool to advance our understanding of the induction of T-cell responses against pathogens such as HIV-1. We utilized a liquid chromatography tandem mass spectrometry workflow including de novo-assisted database searching to define the HLA class I-associated immunopeptidome of HIV-1-infected human cells. We here report for the first time the identification of 75 HIV-1-derived peptides bound to HLA class I complexes that were purified directly from HIV-1-infected human primary CD4(+) T cells and the C8166 human T-cell line. Importantly, one-third of eluted HIV-1 peptides had not been previously known to be presented by HLA class I. Over 82% of the identified sequences originated from viral protein regions for which T-cell responses have previously been reported but for which the precise HLA class I-binding sequences have not yet been defined. These results validate and expand the current knowledge of virus-specific antigenic peptide presentation during HIV-1 infection and provide novel targets for T-cell vaccine development.

Li H, Kreider E, Lopker M, Roberts E, Wang S, Ding W, Kim E, Warrier R, Learn G, Maness N et al. 2015. EARLY ADAPTIVE IMMUNE RESPONSES TO PEPTIDES ENCODED BY THE SIV 5 ' LEADER SEQUENCE REVEAL NOVEL VIRUS-HOST INTERACTIONS AND POTENTIAL NEW TARGETS FOR VACCINE DEVELOPMENT JOURNAL OF MEDICAL PRIMATOLOGY, 44 (5), pp. 324-324.

Deymier MJ, Ende Z, Fenton-May AE, Dilernia DA, Kilembe W, Allen SA, Borrow P, Hunter E. 2015. Heterosexual Transmission of Subtype C HIV-1 Selects Consensus-Like Variants without Increased Replicative Capacity or Interferon-α Resistance. PLoS Pathog, 11 (9), pp. e1005154. | Show Abstract | Read more

Heterosexual transmission of HIV-1 is characterized by a genetic bottleneck that selects a single viral variant, the transmitted/founder (TF), during most transmission events. To assess viral characteristics influencing HIV-1 transmission, we sequenced 167 near full-length viral genomes and generated 40 infectious molecular clones (IMC) including TF variants and multiple non-transmitted (NT) HIV-1 subtype C variants from six linked heterosexual transmission pairs near the time of transmission. Consensus-like genomes sensitive to donor antibodies were selected for during transmission in these six transmission pairs. However, TF variants did not demonstrate increased viral fitness in terms of particle infectivity or viral replicative capacity in activated peripheral blood mononuclear cells (PBMC) and monocyte-derived dendritic cells (MDDC). In addition, resistance of the TF variant to the antiviral effects of interferon-α (IFN-α) was not significantly different from that of non-transmitted variants from the same transmission pair. Thus neither in vitro viral replicative capacity nor IFN-α resistance discriminated the transmission potential of viruses in the quasispecies of these chronically infected individuals. However, our findings support the hypothesis that within-host evolution of HIV-1 in response to adaptive immune responses reduces viral transmission potential.

Bridgeman A, Maelfait J, Davenne T, Partridge T, Peng Y, Mayer A, Dong T, Kaever V, Borrow P, Rehwinkel J. 2015. Viruses transfer the antiviral second messenger cGAMP between cells. Science, 349 (6253), pp. 1228-1232. | Show Abstract | Read more

Cyclic GMP-AMP synthase (cGAS) detects cytosolic DNA during virus infection and induces an antiviral state. cGAS signals by synthesis of a second messenger, cyclic GMP-AMP (cGAMP), which activates stimulator of interferon genes (STING). We show that cGAMP is incorporated into viral particles, including lentivirus and herpesvirus virions, when these are produced in cGAS-expressing cells. Virions transferred cGAMP to newly infected cells and triggered a STING-dependent antiviral program. These effects were independent of exosomes and viral nucleic acids. Our results reveal a way by which a signal for innate immunity is transferred between cells, potentially accelerating and broadening antiviral responses. Moreover, infection of dendritic cells with cGAMP-loaded lentiviruses enhanced their activation. Loading viral vectors with cGAMP therefore holds promise for vaccine development.

Zhang C, Zhou S, Groppelli E, Pellegrino P, Williams I, Borrow P, Chain BM, Jolly C. 2015. Hybrid spreading mechanisms and T cell activation shape the dynamics of HIV-1 infection. PLoS Comput Biol, 11 (4), pp. e1004179. | Show Abstract | Read more

HIV-1 can disseminate between susceptible cells by two mechanisms: cell-free infection following fluid-phase diffusion of virions and by highly-efficient direct cell-to-cell transmission at immune cell contacts. The contribution of this hybrid spreading mechanism, which is also a characteristic of some important computer worm outbreaks, to HIV-1 progression in vivo remains unknown. Here we present a new mathematical model that explicitly incorporates the ability of HIV-1 to use hybrid spreading mechanisms and evaluate the consequences for HIV-1 pathogenenesis. The model captures the major phases of the HIV-1 infection course of a cohort of treatment naive patients and also accurately predicts the results of the Short Pulse Anti-Retroviral Therapy at Seroconversion (SPARTAC) trial. Using this model we find that hybrid spreading is critical to seed and establish infection, and that cell-to-cell spread and increased CD4+ T cell activation are important for HIV-1 progression. Notably, the model predicts that cell-to-cell spread becomes increasingly effective as infection progresses and thus may present a considerable treatment barrier. Deriving predictions of various treatments' influence on HIV-1 progression highlights the importance of earlier intervention and suggests that treatments effectively targeting cell-to-cell HIV-1 spread can delay progression to AIDS. This study suggests that hybrid spreading is a fundamental feature of HIV infection, and provides the mathematical framework incorporating this feature with which to evaluate future therapeutic strategies.

Yue L, Pfafferott KJ, Baalwa J, Conrod K, Dong CC, Chui C, Rong R, Claiborne DT, Prince JL, Tang J et al. 2015. Transmitted virus fitness and host T cell responses collectively define divergent infection outcomes in two HIV-1 recipients. PLoS Pathog, 11 (1), pp. e1004565. | Show Abstract | Read more

Control of virus replication in HIV-1 infection is critical to delaying disease progression. While cellular immune responses are a key determinant of control, relatively little is known about the contribution of the infecting virus to this process. To gain insight into this interplay between virus and host in viral control, we conducted a detailed analysis of two heterosexual HIV-1 subtype A transmission pairs in which female recipients sharing three HLA class I alleles exhibited contrasting clinical outcomes: R880F controlled virus replication while R463F experienced high viral loads and rapid disease progression. Near full-length single genome amplification defined the infecting transmitted/founder (T/F) virus proteome and subsequent sequence evolution over the first year of infection for both acutely infected recipients. T/F virus replicative capacities were compared in vitro, while the development of the earliest cellular immune response was defined using autologous virus sequence-based peptides. The R880F T/F virus replicated significantly slower in vitro than that transmitted to R463F. While neutralizing antibody responses were similar in both subjects, during acute infection R880F mounted a broad T cell response, the most dominant components of which targeted epitopes from which escape was limited. In contrast, the primary HIV-specific T cell response in R463F was focused on just two epitopes, one of which rapidly escaped. This comprehensive study highlights both the importance of the contribution of the lower replication capacity of the transmitted/founder virus and an associated induction of a broad primary HIV-specific T cell response, which was not undermined by rapid epitope escape, to long-term viral control in HIV-1 infection. It underscores the importance of the earliest CD8 T cell response targeting regions of the virus proteome that cannot mutate without a high fitness cost, further emphasizing the need for vaccines that elicit a breadth of T cell responses to conserved viral epitopes.

Gilmour J, Kamali A, Karita E, Kilembe W, Sanders EJ, Anzala O, Allen S, Edward V, Priddy F, Price MA et al. 2014. African Early Infection Cohort as a Platform for Vaccine Discovery: The IAVI Protocol C Experience. AIDS Res Hum Retroviruses, 30 Suppl 1 (S1), pp. A31. | Read more

Armitage AE, Stacey AR, Giannoulatou E, Marshall E, Sturges P, Chatha K, Smith NM, Huang X, Xu X, Pasricha SR et al. 2014. Distinct patterns of hepcidin and iron regulation during HIV-1, HBV, and HCV infections. Proc Natl Acad Sci U S A, 111 (33), pp. 12187-12192. | Show Abstract | Read more

During HIV type-1 (HIV-1), hepatitis C virus (HCV), and hepatitis B virus (HBV) infections, altered iron balance correlates with morbidity. The liver-produced hormone hepcidin dictates systemic iron homeostasis. We measured hepcidin, iron parameters, cytokines, and inflammatory markers in three cohorts: plasma donors who developed acute HIV-1, HBV, or HCV viremia during the course of donations; HIV-1-positive individuals progressing from early to chronic infection; and chronically HIV-1-infected individuals (receiving antiretroviral therapy or untreated). Hepcidin increased and plasma iron decreased during acute HIV-1 infection, as viremia was initially detected. In patients transitioning from early to chronic HIV-1 infection, hepcidin in the first 60 d of infection positively correlated with the later plasma viral load set-point. Hepcidin remained elevated in individuals with untreated chronic HIV-1 infection and in subjects on ART. In contrast to HIV-1, there was no evidence of hepcidin up-regulation or hypoferremia during the primary viremic phases of HCV or HBV infection; serum iron marginally increased during acute HBV infection. In conclusion, hepcidin induction is part of the pathogenically important systemic inflammatory cascade triggered during HIV-1 infection and may contribute to the establishment and maintenance of viral set-point, which is a strong predictor of progression to AIDS and death. However, distinct patterns of hepcidin and iron regulation occur during different viral infections that have particular tissue tropisms and elicit different systemic inflammatory responses. The hypoferremia of acute infection is therefore a pathogen-specific, not universal, phenomenon.

Tandon R, Chew GM, Byron MM, Borrow P, Niki T, Hirashima M, Barbour JD, Norris PJ, Lanteri MC, Martin JN et al. 2014. Galectin-9 is rapidly released during acute HIV-1 infection and remains sustained at high levels despite viral suppression even in elite controllers. AIDS Res Hum Retroviruses, 30 (7), pp. 654-664. | Show Abstract | Read more

Galectin-9 (Gal-9) is a β-galactosidase-binding lectin that promotes apoptosis, tissue inflammation, and T cell immune exhaustion, and alters HIV infection in part through engagement with the T cell immunoglobulin mucin domain-3 (Tim-3) receptor and protein disulfide isomerases (PDI). Gal-9 was initially thought to be an eosinophil attractant, but is now known to mediate multiple complex signaling events that affect T cells in both an immunosuppressive and inflammatory manner. To understand the kinetics of circulating Gal-9 levels during HIV infection we measured Gal-9 in plasma during HIV acquisition, in subjects with chronic HIV infection with differing virus control, and in uninfected individuals. During acute HIV infection, circulating Gal-9 was detected as early as 5 days after quantifiable HIV RNA and tracked plasma levels of interleukin (IL)-10, tumor necrosis factor (TNF)-α, and IL-1β. In chronic HIV infection, Gal-9 levels positively correlated with plasma HIV RNA levels (r=0.29; p=0.023), and remained significantly elevated during suppressive antiretroviral therapy (median: 225.3 pg/ml) and in elite controllers (263.3 pg/ml) compared to age-matched HIV-uninfected controls (54 pg/ml). Our findings identify Gal-9 as a novel component of the first wave of the cytokine storm in acute HIV infection that is sustained at elevated levels in virally suppressed subjects and suggest that Gal-9:Tim-3 crosstalk remains active in elite controllers and antiretroviral (ARV)-suppressed subjects, potentially contributing to ongoing inflammation and persistent T cell dysfunction.

Borrow P, Stacey A, Fenton-May A, Dibben O, Haygreen E, Emmerich T, Kim N, Marshall E, Lavender K, Cohen M et al. 2013. Innate immune responses in acute HIV-1 infection: protective or pathogenic? RETROVIROLOGY, 10 pp. S7-S7.

Clutton G, Yang H, Hancock G, Sande N, Holloway C, Angus B, von Delft A, Barnes E, Borrow P, Pellegrino P et al. 2013. Emergence of a distinct HIV-specific IL-10-producing CD8+ T-cell subset with immunomodulatory functions during chronic HIV-1 infection. Eur J Immunol, 43 (11), pp. 2875-2885. | Show Abstract | Read more

Interleukin-10 (IL-10) plays a key role in regulating proinflammatory immune responses to infection but can interfere with pathogen clearance. Although IL-10 is upregulated throughout HIV-1 infection in multiple cell subsets, whether this is a viral immune evasion strategy or an appropriate response to immune activation is unresolved. Analysis of IL-10 production at the single cell level in 51 chronically infected subjects (31 antiretroviral (ART) naïve and 20 ART treated) showed that a subset of CD8(+) T cells with a CD25(neg) FoxP3(neg) phenotype contributes substantially to IL-10 production in response to HIV-1 gag stimulation. The frequencies of gag-specific IL-10- and IFN-γ-producing T cells in ART-naïve subjects were strongly correlated and the majority of these IL-10(+) CD8(+) T cells co-produced IFN-γ; however, patients with a predominant IL-10(+) /IFN-γ(neg) profile showed better control of viraemia. Depletion of HIV-specific CD8(+) IL-10(+) cells from PBMCs led to upregulation of CD38 on CD14(+) monocytes together with increased IL-6 production, in response to gag stimulation. Increased CD38 expression was positively correlated with the frequency of the IL-10(+) population and was also induced by exposure of monocytes to HIV-1 in vitro. Production of IL-10 by HIV-specific CD8(+) T cells may represent an adaptive regulatory response to monocyte activation during chronic infection.

Armitage AE, Gileadi U, Stacey A, Giannoulatou E, Marshall E, Sturges P, Eddowes L, Cerundolo V, Townsend A, Webster C et al. 2013. HEPCIDIN REGULATION DURING ACUTE INFECTIONS AMERICAN JOURNAL OF HEMATOLOGY, 88 (5), pp. E135-E135.

Berkhout B, Lever A, Wainberg M, Fassati A, Borrow P, Fujii M. 2013. Monsef Benkirane awarded 2013 Ming K. Jeang Foundation Retrovirology Prize: landmark HIV-1 research honoured. Retrovirology, 10 (1), pp. 38. | Read more

Parrish NF, Gao F, Li H, Giorgi EE, Barbian HJ, Parrish EH, Zajic L, Iyer SS, Decker JM, Kumar A et al. 2013. Phenotypic properties of transmitted founder HIV-1. Proc Natl Acad Sci U S A, 110 (17), pp. 6626-6633. | Show Abstract | Read more

Defining the virus-host interactions responsible for HIV-1 transmission, including the phenotypic requirements of viruses capable of establishing de novo infections, could be important for AIDS vaccine development. Previous analyses have failed to identify phenotypic properties other than chemokine receptor 5 (CCR5) and CD4+ T-cell tropism that are preferentially associated with viral transmission. However, most of these studies were limited to examining envelope (Env) function in the context of pseudoviruses. Here, we generated infectious molecular clones of transmitted founder (TF; n = 27) and chronic control (CC; n = 14) viruses of subtypes B (n = 18) and C (n = 23) and compared their phenotypic properties in assays specifically designed to probe the earliest stages of HIV-1 infection. We found that TF virions were 1.7-fold more infectious (P = 0.049) and contained 1.9-fold more Env per particle (P = 0.048) compared with CC viruses. TF viruses were also captured by monocyte-derived dendritic cells 1.7-fold more efficiently (P = 0.035) and more readily transferred to CD4+ T cells (P = 0.025). In primary CD4+ T cells, TF and CC viruses replicated with comparable kinetics; however, when propagated in the presence of IFN-α, TF viruses replicated to higher titers than CC viruses. This difference was significant for subtype B (P = 0.000013) but not subtype C (P = 0.53) viruses, possibly reflecting demographic differences of the respective patient cohorts. Together, these data indicate that TF viruses are enriched for higher Env content, enhanced cell-free infectivity, improved dendritic cell interaction, and relative IFN-α resistance. These viral properties, which likely act in concert, should be considered in the development and testing of AIDS vaccines.

Clark DJ, Catusse J, Stacey A, Borrow P, Gompels UA. 2013. Activation of CCR2+ human proinflammatory monocytes by human herpesvirus-6B chemokine N-terminal peptide. J Gen Virol, 94 (Pt 7), pp. 1624-1635. | Show Abstract | Read more

Human monocytes expressing CCR2 with CD14 and CD16 can mediate antigen presentation, and promote inflammation, brain infiltration and immunosenescence. Recently identified roles are in human immunodeficiency virus infection, tuberculosis and parasitic disease. Human herpesvirus 6B (HHV-6B) encodes a chemokine, U83B, which is monospecific for CCR2, and is distinct from the related HHV-6A U83A, which activates CCR1, CCR4, CCR5, CCR6 and CCR8 on immune effector cells and dendritic cells. These differences could alter leukocyte-subset recruitment for latent/lytic replication and associated neuroinflammatory pathology. Therefore, cellular interactions between U83A and U83B could help dictate potential tropism differences between these viruses. U83A specificity is maintained in the 38-residue N-terminal spliced-truncated form. Here, we sought to determine the basis for the chemokine receptor specificity differences and identify possible applications. To do this we first analysed variation in a natural host population in sub-Saharan Africa where both viruses are equally prevalent and compared these to global strains. Analyses of U83 N-terminal variation in 112 HHV-6A and HHV-6B infections identified 6/38 U83A or U83B-specific residues. We also identified a unique single U83A-specific substitution in one U83B sequence, 'U83BA'. Next, the variation effects were tested by deriving N-terminal (NT) 17-mer peptides and assaying activation of ex vivo human leukocytes, the natural host and cellular target. Chemotaxis of CCR2+ leukocytes was potently induced by U83B-NT, but not U83BA-NT or U83A-NT. Analyses of the U83B-NT activated population identified migrated CCR2+, but not CCR5+, leukocytes. The U83BA-NT asparagine-lysine14 substitution disrupted activity, thus defining CCR2 specificity and acting as a main determinant for HHV-6A/B differences in cellular interactions. A flow-cytometry-based shape-change assay was designed, and used to provide further evidence that U83B-NT could activate CCR2+CD14+CD16+ monocytes. This defines a potential antiviral target for HHV-6A/B disease and novel peptide immunomodulator for proinflammatory monocytes.

Murphy MK, Yue L, Pan R, Boliar S, Sethi A, Tian J, Pfafferot K, Karita E, Allen SA, Cormier E et al. 2013. Viral escape from neutralizing antibodies in early subtype A HIV-1 infection drives an increase in autologous neutralization breadth. PLoS Pathog, 9 (2), pp. e1003173. | Show Abstract | Read more

Antibodies that neutralize (nAbs) genetically diverse HIV-1 strains have been recovered from a subset of HIV-1 infected subjects during chronic infection. Exact mechanisms that expand the otherwise narrow neutralization capacity observed during early infection are, however, currently undefined. Here we characterized the earliest nAb responses in a subtype A HIV-1 infected Rwandan seroconverter who later developed moderate cross-clade nAb breadth, using (i) envelope (Env) glycoproteins from the transmitted/founder virus and twenty longitudinal nAb escape variants, (ii) longitudinal autologous plasma, and (iii) autologous monoclonal antibodies (mAbs). Initially, nAbs targeted a single region of gp120, which flanked the V3 domain and involved the alpha2 helix. A single amino acid change at one of three positions in this region conferred early escape. One immunoglobulin heavy chain and two light chains recovered from autologous B cells comprised two mAbs, 19.3H-L1 and 19.3H-L3, which neutralized the founder Env along with one or three of the early escape variants carrying these mutations, respectively. Neither mAb neutralized later nAb escape or heterologous Envs. Crystal structures of the antigen-binding fragments (Fabs) revealed flat epitope contact surfaces, where minimal light chain mutation in 19.3H-L3 allowed for additional antigenic interactions. Resistance to mAb neutralization arose in later Envs through alteration of two glycans spatially adjacent to the initial escape signatures. The cross-neutralizing nAbs that ultimately developed failed to target any of the defined V3-proximal changes generated during the first year of infection in this subject. Our data demonstrate that this subject's first recognized nAb epitope elicited strain-specific mAbs, which incrementally acquired autologous breadth, and directed later B cell responses to target distinct portions of Env. This immune re-focusing could have triggered the evolution of cross-clade antibodies and suggests that exposure to a specific sequence of immune escape variants might promote broad humoral responses during HIV-1 infection.

Yates NL, Stacey AR, Nolen TL, Vandergrift NA, Moody MA, Montefiori DC, Weinhold KJ, Blattner WA, Borrow P, Shattock R et al. 2013. HIV-1 gp41 envelope IgA is frequently elicited after transmission but has an initial short response half-life. Mucosal Immunol, 6 (4), pp. 692-703. | Show Abstract | Read more

Prevention of HIV-1 transmission at mucosal surfaces will likely require durable pre-existing mucosal anti-HIV-1 antibodies (Abs). Defining the ontogeny, specificities and potentially protective nature of the initial mucosal virus-specific B-cell response will be critical for understanding how to induce protective Ab responses by vaccination. Genital fluids from patients within the earliest stages of acute HIV-1 infection (Fiebig I-VI) were examined for multiple anti-HIV specificities. Gp41 (but not gp120) Env immunoglobulin (Ig)A Abs were frequently elicited in both plasma and mucosal fluids within the first weeks of transmission. However, shortly after induction, these initial mucosal gp41 Env IgA Abs rapidly declined with a t(½) of ∼2.7 days. B-cell-activating factor belonging to the TNF family (BAFF) was elevated immediately preceding the appearance of gp41 Abs, likely contributing to an initial T-independent Ab response. HIV-1 transmission frequently elicits mucosal HIV-1 envelope-specific IgA responses targeted to gp41 that have a short half-life.

Fenton-May AE, Dibben O, Emmerich T, Ding H, Pfafferott K, Aasa-Chapman MM, Pellegrino P, Williams I, Cohen MS, Gao F et al. 2013. Relative resistance of HIV-1 founder viruses to control by interferon-alpha. Retrovirology, 10 (1), pp. 146. | Show Abstract | Read more

BACKGROUND: Following mucosal human immunodeficiency virus type 1 (HIV-1) transmission, type 1 interferons (IFNs) are rapidly induced at sites of initial virus replication in the mucosa and draining lymph nodes. However, the role played by IFN-stimulated antiviral activity in restricting HIV-1 replication during the initial stages of infection is not clear. We hypothesized that if type 1 IFNs exert selective pressure on HIV-1 replication in the earliest stages of infection, the founder viruses that succeed in establishing systemic infection would be more IFN-resistant than viruses replicating during chronic infection, when type 1 IFNs are produced at much lower levels. To address this hypothesis, the relative resistance of virus isolates derived from HIV-1-infected individuals during acute and chronic infection to control by type 1 IFNs was analysed. RESULTS: The replication of plasma virus isolates generated from subjects acutely infected with HIV-1 and molecularly cloned founder HIV-1 strains could be reduced but not fully suppressed by type 1 IFNs in vitro. The mean IC50 value for IFNα2 (22 U/ml) was lower than that for IFNβ (346 U/ml), although at maximally-inhibitory concentrations both IFN subtypes inhibited virus replication to similar extents. Individual virus isolates exhibited differential susceptibility to inhibition by IFNα2 and IFNβ, likely reflecting variation in resistance to differentially up-regulated IFN-stimulated genes. Virus isolates from subjects acutely infected with HIV-1 were significantly more resistant to in vitro control by IFNα than virus isolates generated from the same individuals during chronic, asymptomatic infection. Viral IFN resistance declined rapidly after the acute phase of infection: in five subjects, viruses derived from six-month consensus molecular clones were significantly more sensitive to the antiviral effects of IFNs than the corresponding founder viruses. CONCLUSIONS: The establishment of systemic HIV-1 infection by relatively IFNα-resistant founder viruses lends strong support to the hypothesis that IFNα plays an important role in the control of HIV-1 replication during the earliest stages of infection, prior to systemic viral spread. These findings suggest that it may be possible to harness the antiviral activity of type 1 IFNs in prophylactic and potentially also therapeutic strategies to combat HIV-1 infection.

Berkhout B, Benkirane M, Lever A, Wainberg M, Fassati A, Borrow P, Fujii M, Sriskantharajah S, Cockerill M. 2013. Obituary: Kuan-Teh Jeang. Retrovirology, 10 (1), pp. 28. | Show Abstract | Read more

Dear colleagues: Our loyal friend Kuan-Teh Jeang, "Teh" to friends and colleagues, passed away unexpectedly at the age of 54 on the evening of January 27, 2013. Great shock and sorrow was apparent in the avalanche of email messages by the very many international colleagues with whom Teh interacted over the years. Many of us came to know Teh as an energetic and gifted scientist for whom we had much respect and affection.

Liu MK, Hawkins N, Ritchie AJ, Ganusov VV, Whale V, Brackenridge S, Li H, Pavlicek JW, Cai F, Rose-Abrahams M et al. 2013. Vertical T cell immunodominance and epitope entropy determine HIV-1 escape. J Clin Invest, 123 (1), pp. 380-393. | Show Abstract | Read more

HIV-1 accumulates mutations in and around reactive epitopes to escape recognition and killing by CD8+ T cells. Measurements of HIV-1 time to escape should therefore provide information on which parameters are most important for T cell-mediated in vivo control of HIV-1. Primary HIV-1-specific T cell responses were fully mapped in 17 individuals, and the time to virus escape, which ranged from days to years, was measured for each epitope. While higher magnitude of an individual T cell response was associated with more rapid escape, the most significant T cell measure was its relative immunodominance measured in acute infection. This identified subject-level or "vertical" immunodominance as the primary determinant of in vivo CD8+ T cell pressure in HIV-1 infection. Conversely, escape was slowed significantly by lower population variability, or entropy, of the epitope targeted. Immunodominance and epitope entropy combined to explain half of all the variability in time to escape. These data explain how CD8+ T cells can exert significant and sustained HIV-1 pressure even when escape is very slow and that within an individual, the impacts of other T cell factors on HIV-1 escape should be considered in the context of immunodominance.

Frleta D, Ochoa CE, Kramer HB, Khan SA, Stacey AR, Borrow P, Kessler BM, Haynes BF, Bhardwaj N. 2012. HIV-1 infection-induced apoptotic microparticles inhibit human DCs via CD44. J Clin Invest, 122 (12), pp. 4685-4697. | Show Abstract | Read more

Acute HIV-1 infection results in dysregulated immunity, which contributes to poor control of viral infection. DCs are key regulators of both adaptive and innate immune responses needed for controlling HIV-1, and we surmised that factors elicited during acute HIV-1 infection might impede DC function. We derived immature DCs from healthy donor peripheral blood monocytes and treated them with plasma from uninfected control donors and donors with acute HIV-1 infections. We found that the plasma from patients with HIV specifically inhibited DC function. This suppression was mediated by elevated apoptotic microparticles derived from dying cells during acute HIV-1 infection. Apoptotic microparticles bound to and inhibited DCs through the hyaluronate receptor CD44. These data suggest that targeting this CD44-mediated inhibition by apoptotic microparticles could be a novel strategy to potentiate DC activation of HIV-specific immunity.

Frleta D, Ochoa CE, Kramer HB, Khan SA, Stacey AR, Borrow P, Kessler BM, Haynes BF, Bhardwaj N. 2012. Apoptotic microparticles generated during acute HIV-1 infection inhibit human dendritic cells via CD44 RETROVIROLOGY, 9 (Suppl 2), pp. P183-P183. | Read more

Brown RJ, Hudson N, Wilson G, Rehman SU, Jabbari S, Hu K, Tarr AW, Borrow P, Joyce M, Lewis J et al. 2012. Hepatitis C virus envelope glycoprotein fitness defines virus population composition following transmission to a new host. J Virol, 86 (22), pp. 11956-11966. | Show Abstract | Read more

Genetic variability is a hallmark of RNA virus populations. However, transmission to a new host often results in a marked decrease in population diversity. This genetic bottlenecking is observed during hepatitis C virus (HCV) transmission and can arise via a selective sweep or through the founder effect. To model HCV transmission, we utilized chimeric SCID/Alb-uPA mice with transplanted human hepatocytes and infected them with a human serum HCV inoculum. E1E2 glycoprotein gene sequences in the donor inoculum and recipient mice were determined following single-genome amplification (SGA). In independent experiments, using mice with liver cells grafted from different sources, an E1E2 variant undetectable in the source inoculum was selected for during transmission. Bayesian coalescent analyses indicated that this variant arose in the inoculum pretransmission. Transmitted variants that established initial infection harbored key substitutions in E1E2 outside HVR1. Notably, all posttransmission E1E2s had lost a potential N-linked glycosylation site (PNGS) in E2. In lentiviral pseudoparticle assays, the major posttransmission E1E2 variant conferred an increased capacity for entry compared to the major variant present in the inoculum. Together, these data demonstrate that increased envelope glycoprotein fitness can drive selective outgrowth of minor variants posttransmission and that loss of a PNGS is integral to this improved phenotype. Mathematical modeling of the dynamics of competing HCV variants indicated that relatively modest differences in glycoprotein fitness can result in marked shifts in virus population composition. Overall, these data provide important insights into the dynamics and selection of HCV populations during transmission.

Ribeiro-dos-Santos P, Turnbull EL, Monteiro M, Legrand A, Conrod K, Baalwa J, Pellegrino P, Shaw GM, Williams I, Borrow P, Rocha B. 2012. Chronic HIV infection affects the expression of the 2 transcription factors required for CD8 T-cell differentiation into cytolytic effectors. Blood, 119 (21), pp. 4928-4938. | Show Abstract | Read more

CD8 T cells lose the capacity to control HIV infection, but the extent of the impairment of CD8 T-cell functions and the mechanisms that underlie it remain controversial. Here we report an extensive ex vivo analysis of HIV-specific CD8 T cells, covering the expression of 16 different molecules involved in CD8 function or differentiation. This approach gave remarkably homogeneous readouts in different donors and showed that CD8 dysfunction in chronic HIV infection was much more severe than described previously: some Ifng transcription was observed, but most cells lost the expression of all cytolytic molecules and Eomesodermin and T-bet by chronic infection. These results reveal a cellular mechanism explaining the dysfunction of CD8 T cells during chronic HIV infection, as CD8 T cells are known to maintain some functionality when either of these transcription factors is present, but to lose all cytotoxic activity when both are not expressed. Surprisingly, they also show that chronic HIV and lymphocytic choriomeningitis virus infections have a very different impact on fundamental T-cell functions, "exhausted" lymphocytic choriomeningitis virus-specific cells losing the capacity to secrete IFN-γ but maintaining some cytotoxic activity as granzyme B and FasL are overexpressed and, while down-regulating T-bet, up-regulating Eomesodermin expression.

Riou C, Ganusov VV, Campion S, Mlotshwa M, Liu MK, Whale VE, Goonetilleke N, Borrow P, Ferrari G, Betts MR et al. 2012. Distinct kinetics of Gag-specific CD4+ and CD8+ T cell responses during acute HIV-1 infection. J Immunol, 188 (5), pp. 2198-2206. | Show Abstract | Read more

HIV infection is characterized by a gradual deterioration of immune function, mainly in the CD4 compartment. To better understand the dynamics of HIV-specific T cells, we analyzed the kinetics and polyfunctional profiles of Gag-specific CD4(+) and CD8(+) T cell responses in 12 subtype C-infected individuals with different disease-progression profiles, ranging from acute to chronic HIV infection. The frequencies of Gag-responsive CD4(+) and CD8(+) T cells showed distinct temporal kinetics. The peak frequency of Gag-responsive IFN-γ(+)CD4(+) T cells was observed at a median of 28 d (interquartile range: 21-81 d) post-Fiebig I/II staging, whereas Gag-specific IFN-γ(+)CD8(+) T cell responses peaked at a median of 253 d (interquartile range: 136-401 d) and showed a significant biphasic expansion. The proportion of TNF-α-expressing cells within the IFN-γ(+)CD4(+) T cell population increased (p = 0.001) over time, whereas TNF-α-expressing cells within IFN-γ(+)CD8(+) T cells declined (p = 0.005). Both Gag-responsive CD4(+) and CD8(+) T cells showed decreased Ki67 expression within the first 120 d post-Fiebig I/II staging. Prior to the disappearance of Gag-responsive Ki67(+)CD4(+) T cells, these cells positively correlated (p = 0.00038) with viremia, indicating that early Gag-responsive CD4 events are shaped by viral burden. No such associations were observed in the Gag-specific CD8(+) T cell compartment. Overall, these observations indicated that circulating Gag-responsive CD4(+) and CD8(+) T cell frequencies and functions are not synchronous, and properties change rapidly at different tempos during early HIV infection.

Pelak K, Need AC, Fellay J, Shianna KV, Feng S, Urban TJ, Ge D, De Luca A, Martinez-Picado J, Wolinsky SM et al. 2011. Correction: Copy Number Variation of KIR Genes Influences HIV-1 Control. PLoS Biol, 9 (12), | Show Abstract | Read more

[This corrects the article on p. e1001208 in vol. 9.].

Pelak K, Need AC, Fellay J, Shianna KV, Feng S, Urban TJ, Ge D, De Luca A, Martinez-Picado J, Wolinsky SM et al. 2011. Copy number variation of KIR genes influences HIV-1 control. PLoS Biol, 9 (11), pp. e1001208. | Show Abstract | Read more

A genome-wide screen for large structural variants showed that a copy number variant (CNV) in the region encoding killer cell immunoglobulin-like receptors (KIR) associates with HIV-1 control as measured by plasma viral load at set point in individuals of European ancestry. This CNV encompasses the KIR3DL1-KIR3DS1 locus, encoding receptors that interact with specific HLA-Bw4 molecules to regulate the activation of lymphocyte subsets including natural killer (NK) cells. We quantified the number of copies of KIR3DS1 and KIR3DL1 in a large HIV-1 positive cohort, and showed that an increase in KIR3DS1 count associates with a lower viral set point if its putative ligand is present (p = 0.00028), as does an increase in KIR3DL1 count in the presence of KIR3DS1 and appropriate ligands for both receptors (p = 0.0015). We further provide functional data that demonstrate that NK cells from individuals with multiple copies of KIR3DL1, in the presence of KIR3DS1 and the appropriate ligands, inhibit HIV-1 replication more robustly, and associated with a significant expansion in the frequency of KIR3DS1+, but not KIR3DL1+, NK cells in their peripheral blood. Our results suggest that the relative amounts of these activating and inhibitory KIR play a role in regulating the peripheral expansion of highly antiviral KIR3DS1+ NK cells, which may determine differences in HIV-1 control following infection.

Ganusov VV, Goonetilleke N, Liu MK, Ferrari G, Shaw GM, McMichael AJ, Borrow P, Korber BT, Perelson AS. 2011. Fitness costs and diversity of the cytotoxic T lymphocyte (CTL) response determine the rate of CTL escape during acute and chronic phases of HIV infection. J Virol, 85 (20), pp. 10518-10528. | Show Abstract | Read more

HIV-1 often evades cytotoxic T cell (CTL) responses by generating variants that are not recognized by CTLs. We used single-genome amplification and sequencing of complete HIV genomes to identify longitudinal changes in the transmitted/founder virus from the establishment of infection to the viral set point at 1 year after the infection. We found that the rate of viral escape from CTL responses in a given patient decreases dramatically from acute infection to the viral set point. Using a novel mathematical model that tracks the dynamics of viral escape at multiple epitopes, we show that a number of factors could potentially contribute to a slower escape in the chronic phase of infection, such as a decreased magnitude of epitope-specific CTL responses, an increased fitness cost of escape mutations, or an increased diversity of the CTL response. In the model, an increase in the number of epitope-specific CTL responses can reduce the rate of viral escape from a given epitope-specific CTL response, particularly if CD8+ T cells compete for killing of infected cells or control virus replication nonlytically. Our mathematical framework of viral escape from multiple CTL responses can be used to predict the breadth and magnitude of HIV-specific CTL responses that need to be induced by vaccination to reduce (or even prevent) viral escape following HIV infection.

Borrow P. 2011. Innate immunity in acute HIV-1 infection. Curr Opin HIV AIDS, 6 (5), pp. 353-363. | Show Abstract | Read more

PURPOSE OF REVIEW: Acute HIV-1 infection (AHI) is composed of the eclipse phase, during which the transmitted virus struggles to avoid eradication and achieve amplification/spread; the expansion phase when virus disseminates and undergoes exponential replication associated with extensive CD4⁺ T-cell destruction; and the containment phase when set-point levels of viremia and immune activation are established. The importance of interactions between HIV-1 and innate responses in determining events throughout AHI is increasingly recognized, and is reviewed here. RECENT FINDINGS: During the eclipse phase, HIV-1 subverts dendritic cell functions to promote its replication at mucosal sites and employs multiple strategies to minimize control by type 1 interferons. Systemic virus dissemination is associated with widespread activation of innate responses which fuels HIV-1 replication. To minimize the protective effects of innate responses, HIV-1 resists control by natural killer cells and may impair innate regulation of adaptive responses. Innate responses remain chronically activated after HIV-1 containment which is thought to drive HIV-1 pathogenesis. SUMMARY: Innate responses are pivotal determinants of events at all stages of AHI. Increased understanding of mechanisms involved in innate control of HIV-1 and pathways regulating innate activation during HIV-1 infection could facilitate development of novel approaches to combating this infection.

Breen EC, Reynolds SM, Cox C, Jacobson LP, Magpantay L, Mulder CB, Dibben O, Margolick JB, Bream JH, Sambrano E et al. 2011. Multisite comparison of high-sensitivity multiplex cytokine assays. Clin Vaccine Immunol, 18 (8), pp. 1229-1242. | Show Abstract | Read more

The concentrations of cytokines in human serum and plasma can provide valuable information about in vivo immune status, but low concentrations often require high-sensitivity assays to permit detection. The recent development of multiplex assays, which can measure multiple cytokines in one small sample, holds great promise, especially for studies in which limited volumes of stored serum or plasma are available. Four high-sensitivity cytokine multiplex assays on a Luminex (Bio-Rad, BioSource, Linco) or electrochemiluminescence (Meso Scale Discovery) platform were evaluated for their ability to detect circulating concentrations of 13 cytokines, as well as for laboratory and lot variability. Assays were performed in six different laboratories utilizing archived serum from HIV-uninfected and -infected subjects from the Multicenter AIDS Cohort Study (MACS) and the Women's Interagency HIV Study (WIHS) and commercial plasma samples spanning initial HIV viremia. In a majority of serum samples, interleukin-6 (IL-6), IL-8, IL-10, and tumor necrosis factor alpha were detectable with at least three kits, while IL-1β was clearly detected with only one kit. No single multiplex panel detected all cytokines, and there were highly significant differences (P < 0.001) between laboratories and/or lots with all kits. Nevertheless, the kits generally detected similar patterns of cytokine perturbation during primary HIV viremia. This multisite comparison suggests that current multiplex assays vary in their ability to measure serum and/or plasma concentrations of cytokines and may not be sufficiently reproducible for repeated determinations over a long-term study or in multiple laboratories but may be useful for longitudinal studies in which relative, rather than absolute, changes in cytokines are important.

Turnbull EL, Baalwa J, Conrod KE, Wang S, Wei X, Wong M, Turner J, Pellegrino P, Williams I, Shaw GM, Borrow P. 2011. Escape is a more common mechanism than avidity reduction for evasion of CD8+ T cell responses in primary human immunodeficiency virus type 1 infection. Retrovirology, 8 (1), pp. 41. | Show Abstract | Read more

BACKGROUND: CD8+ T cells play an important role in control of viral replication during acute and early human immunodeficiency virus type 1 (HIV-1) infection, contributing to containment of the acute viral burst and establishment of the prognostically-important persisting viral load. Understanding mechanisms that impair CD8+ T cell-mediated control of HIV replication in primary infection is thus of importance. This study addressed the relative extent to which HIV-specific T cell responses are impacted by viral mutational escape versus reduction in response avidity during the first year of infection. RESULTS: 18 patients presenting with symptomatic primary HIV-1 infection, most of whom subsequently established moderate-high persisting viral loads, were studied. HIV-specific T cell responses were mapped in each individual and responses to a subset of optimally-defined CD8+ T cell epitopes were followed from acute infection onwards to determine whether they were escaped or declined in avidity over time. During the first year of infection, sequence variation occurred in/around 26/33 epitopes studied (79%). In 82% of cases of intra-epitopic sequence variation, the mutation was confirmed to confer escape, although T cell responses were subsequently expanded to variant sequences in some cases. In contrast, < 10% of responses to index sequence epitopes declined in functional avidity over the same time-frame, and a similar proportion of responses actually exhibited an increase in functional avidity during this period. CONCLUSIONS: Escape appears to constitute a much more important means of viral evasion of CD8+ T cell responses in acute and early HIV infection than decline in functional avidity of epitope-specific T cells. These findings support the design of vaccines to elicit T cell responses that are difficult for the virus to escape.

Haddow LJ, Dibben O, Moosa MY, Borrow P, Easterbrook PJ. 2011. Circulating inflammatory biomarkers can predict and characterize tuberculosis-associated immune reconstitution inflammatory syndrome. AIDS, 25 (9), pp. 1163-1174. | Show Abstract | Read more

OBJECTIVE: To identify inflammatory biomarker profiles during paradoxical and unmasking tuberculosis-associated immune reconstitution inflammatory syndrome (TB-IRIS), and determine whether differences in biomarkers prior to antiretroviral therapy (ART) predict subsequent development of TB-IRIS. DESIGN: Case-control study within a cohort of patients initiating ART in South Africa (n = 498). METHODS: Participants were followed up for 24 weeks for development of TB-IRIS. Plasma samples were collected at baseline and presentation with symptoms. Groups of cases and controls were as follows: pre-ART TB and developed paradoxical TB-IRIS (n = 9); pre-ART TB but no IRIS (n = 12); no pre-ART TB but developed unmasking TB-IRIS (n = 13); no pre-ART TB and no TB or IRIS during treatment (n = 12). Concentrations of 18 cytokines and chemokines, and C-reactive protein (CRP), were measured and compared. RESULTS: Event samples were drawn a median of 28 days after ART initiation [interquartile range (IQR) 14-56 days]. During paradoxical TB-IRIS events, there were lower median concentrations of interleukin-10 [IL-10; 22.1 (IQR 15.3-34.9) vs. 82.2 (29.4-128.4) pg/ml, P = 0.047] and monocyte chemotactic protein-1 [MCP-1; 27.6 (20.0-29.7) vs. 71.4 (40.6-77.8) pg/ml, P = 0.005], and higher CRP: IL-10 ratio [2.2 × 10³ (1.8-3.4) vs. 0.3 × 10³ (0.2-0.5), P = 0.003] than in controls. Patients who developed unmasking TB-IRIS had higher median pre-ART levels of CRP [25 (8-47) vs. 6 (lower limit of detection, LLD-12) mg/l, P = 0.046] and interferon gamma (IFN-γ) [9.1 (4.4-24.7) vs. 0.9 (LLD-8.7) pg/ml, P = 0.032] than controls. CONCLUSION: Patients with unmasking TB-IRIS had higher pre-ART levels of plasma IFN-γ and CRP, consistent with preexisting subclinical TB. Paradoxical TB-IRIS was associated with lower levels of biomarkers of monocyte and regulatory T-cell activity, and higher CRP.

Ganusov V, Goonetilleke N, Liu M, Ferrari G, Shaw G, McMichael A, Borrow P, Korber B, Perelson A. 2011. Fitness costs and diversity of CTL response determine the rate of CTL escape during the acute and chronic phases of HIV infection JOURNAL OF IMMUNOLOGY, 186

Breen E, Reynolds S, Cox C, Jacobson L, Magpantay L, Mulder C, Dibben O, Margolick J, Bream J, Sambrano E et al. 2011. Performance of Luminex and MSD high-sensitivity multiplex cytokine assays across multiple lots and laboratories JOURNAL OF IMMUNOLOGY, 186

Corrah TW, Goonetilleke N, Kopycinski J, Deeks SG, Cohen MS, Borrow P, McMichael A, Brackenridge S. 2011. Reappraisal of the relationship between the HIV-1-protective single-nucleotide polymorphism 35 kilobases upstream of the HLA-C gene and surface HLA-C expression. J Virol, 85 (7), pp. 3367-3374. | Show Abstract | Read more

Previous studies have found an association between a single-nucleotide polymorphism 35 kb upstream of the HLA-C locus (-35 SNP), HLA-C expression, and HIV-1 set point viral loads. We show that the difference in HLA-C expression across -35 SNP genotypes can be attributed primarily to the very low expression of a single allelic product, HLA-Cw7, which is a common HLA type. We suggest that association of the -35 SNP and HIV-1 load manifests as a result of linkage disequilibrium of this polymorphism with both favorable and unfavorable HLA-C and -B alleles.

Mahlokozera T, Kang HH, Goonetilleke N, Stacey AR, Lovingood RV, Denny TN, Kalilani L, Bunn JEG, Meshnick SR, Borrow P et al. 2011. The magnitude and kinetics of the mucosal HIV-specific CD8+ T lymphocyte response and virus RNA load in breast milk PLoS ONE, 6 (8), | Show Abstract | Read more

Background: The risk of postnatal HIV transmission is associated with the magnitude of the milk virus load. While HIV-specific cellular immune responses control systemic virus load and are detectable in milk, the contribution of these responses to the control of virus load in milk is unknown. Methods: We assessed the magnitude of the immunodominant GagRY11 and subdominant EnvKY9-specific CD8+ T lymphocyte response in blood and milk of 10 A*3002+, HIV-infected Malawian women throughout the period of lactation and correlated this response to milk virus RNA load and markers of breast inflammation. Results: The magnitude and kinetics of the HIV-specific CD8+ T lymphocyte responses were discordant in blood and milk of the right and left breast, indicating independent regulation of these responses in each breast. However, there was no correlation between the magnitude of the HIV-specific CD8+ T lymphocyte response and the milk virus RNA load. Further, there was no correlation between the magnitude of this response and markers of breast inflammation. Conclusions: The magnitude of the HIV-specific CD8+ T lymphocyte response in milk does not appear to be solely determined by the milk virus RNA load and is likely only one of the factors contributing to maintenance of low virus load in milk. © 2011 Mahlokozera et al.

Cited:

31

Scopus

Borrow P. 2011. Innate immunity in acute HIV-1 infection Current Opinion in HIV and AIDS, 6 (5), pp. 353-363. | Show Abstract | Read more

Purpose of review: Acute HIV-1 infection (AHI) is composed of the eclipse phase, during which the transmitted virus struggles to avoid eradication and achieve amplification/spread; the expansion phase when virus disseminates and undergoes exponential replication associated with extensive CD4 T-cell destruction; and the containment phase when set-point levels of viremia and immune activation are established. The importance of interactions between HIV-1 and innate responses in determining events throughout AHI is increasingly recognized, and is reviewed here. Recent findings: During the eclipse phase, HIV-1 subverts dendritic cell functions to promote its replication at mucosal sites and employs multiple strategies to minimize control by type 1 interferons. Systemic virus dissemination is associated with widespread activation of innate responses which fuels HIV-1 replication. To minimize the protective effects of innate responses, HIV-1 resists control by natural killer cells and may impair innate regulation of adaptive responses. Innate responses remain chronically activated after HIV-1 containment which is thought to drive HIV-1 pathogenesis. Summary: Innate responses are pivotal determinants of events at all stages of AHI. Increased understanding of mechanisms involved in innate control of HIV-1 and pathways regulating innate activation during HIV-1 infection could facilitate development of novel approaches to combating this infection. © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins.

Mahlokozera T, Kang HH, Goonetilleke N, Stacey AR, Lovingood RV, Denny TN, Kalilani L, Bunn JE, Meshnick SR, Borrow P et al. 2011. The magnitude and kinetics of the mucosal HIV-specific CD8+ T lymphocyte response and virus RNA load in breast milk. PLoS One, 6 (8), pp. e23735. | Show Abstract | Read more

BACKGROUND: The risk of postnatal HIV transmission is associated with the magnitude of the milk virus load. While HIV-specific cellular immune responses control systemic virus load and are detectable in milk, the contribution of these responses to the control of virus load in milk is unknown. METHODS: We assessed the magnitude of the immunodominant GagRY11 and subdominant EnvKY9-specific CD8+ T lymphocyte response in blood and milk of 10 A*3002+, HIV-infected Malawian women throughout the period of lactation and correlated this response to milk virus RNA load and markers of breast inflammation. RESULTS: The magnitude and kinetics of the HIV-specific CD8+ T lymphocyte responses were discordant in blood and milk of the right and left breast, indicating independent regulation of these responses in each breast. However, there was no correlation between the magnitude of the HIV-specific CD8+ T lymphocyte response and the milk virus RNA load. Further, there was no correlation between the magnitude of this response and markers of breast inflammation. CONCLUSIONS: The magnitude of the HIV-specific CD8+ T lymphocyte response in milk does not appear to be solely determined by the milk virus RNA load and is likely only one of the factors contributing to maintenance of low virus load in milk.

Cited:

33

Scopus

Haddow LJ, Dibben O, Moosa MYS, Borrow P, Easterbrook PJ. 2011. Circulating inflammatory biomarkers can predict and characterize tuberculosis-associated immune reconstitution inflammatory syndrome AIDS, 25 (9), pp. 1163-1174. | Show Abstract | Read more

Objective: To identify inflammatory biomarker profiles during paradoxical and unmasking tuberculosis-associated immune reconstitution inflammatory syndrome (TB-IRIS), and determine whether differences in biomarkers prior to antiretroviral therapy (ART) predict subsequent development of TB-IRIS. DESIGN:: Case-control study within a cohort of patients initiating ART in South Africa (n = 498). METHODS:: Participants were followed up for 24 weeks for development of TB-IRIS. Plasma samples were collected at baseline and presentation with symptoms. Groups of cases and controls were as follows: pre-ART TB and developed paradoxical TB-IRIS (n = 9); pre-ART TB but no IRIS (n = 12); no pre-ART TB but developed unmasking TB-IRIS (n = 13); no pre-ART TB and no TB or IRIS during treatment (n = 12). Concentrations of 18 cytokines and chemokines, and C-reactive protein (CRP), were measured and compared. Results: Event samples were drawn a median of 28 days after ART initiation [interquartile range (IQR) 14-56 days]. During paradoxical TB-IRIS events, there were lower median concentrations of interleukin-10 [IL-10; 22.1 (IQR 15.3-34.9) vs. 82.2 (29.4-128.4) pg/ml, P = 0.047] and monocyte chemotactic protein-1 [MCP-1; 27.6 (20.0-29.7) vs. 71.4 (40.6-77.8) pg/ml, P = 0.005], and higher CRP: IL-10 ratio [2.2 × 10 (1.8-3.4) vs. 0.3 × 10 (0.2-0.5), P = 0.003] than in controls. Patients who developed unmasking TB-IRIS had higher median pre-ART levels of CRP [25 (8-47) vs. 6 (lower limit of detection, LLD-12) mg/l, P = 0.046] and interferon gamma (IFN-γ) [9.1 (4.4-24.7) vs. 0.9 (LLD-8.7) pg/ml, P = 0.032] than controls. Conclusion: Patients with unmasking TB-IRIS had higher pre-ART levels of plasma IFN-γ and CRP, consistent with preexisting subclinical TB. Paradoxical TB-IRIS was associated with lower levels of biomarkers of monocyte and regulatory T-cell activity, and higher CRP. © 2011 Wolters Kluwer Health - Lippincott Williams & Wilkins.

Gay C, Dibben O, Anderson JA, Stacey A, Mayo AJ, Norris PJ, Kuruc JD, Salazar-Gonzalez JF, Li H, Keele BF et al. 2011. Cross-sectional detection of acute HIV infection: timing of transmission, inflammation and antiretroviral therapy. PLoS One, 6 (5), pp. e19617. | Show Abstract | Read more

BACKGROUND: Acute HIV infection (AHI) is a critical phase of infection when irreparable damage to the immune system occurs and subjects are very infectious. We studied subjects with AHI prospectively to develop better treatment and public health interventions. METHODS: Cross-sectional screening was employed to detect HIV RNA positive, antibody negative subjects. Date of HIV acquisition was estimated from clinical history and correlated with sequence diversity assessed by single genome amplification (SGA). Twenty-two cytokines/chemokines were measured from enrollment through week 24. RESULTS: Thirty-seven AHI subjects were studied. In 7 participants with limited exposure windows, the median exposure to HIV occurred 14 days before symptom onset. Lack of viral sequence diversification confirmed the short duration of infection. Transmission dates estimated by SGA/sequencing using molecular clock models correlated with transmission dates estimated by symptom onset in individuals infected with single HIV variants (mean of 28 versus 33 days). Only 10 of 22 cytokines/chemokines were significantly elevated among AHI participants at enrollment compared to uninfected controls, and only 4 participants remained seronegative at enrollment. DISCUSSION: The results emphasize the difficulty in recruiting subjects early in AHI. Viral sequence diversity proved accurate in estimating time of infection. Regardless of aggressive screening, peak viremia and inflammation occurred before enrollment and potential intervention. Given the personal and public health importance, improved AHI detection is urgently needed.

Ferrari G, Korber B, Goonetilleke N, Liu MK, Turnbull EL, Salazar-Gonzalez JF, Hawkins N, Self S, Watson S, Betts MR et al. 2011. Relationship between functional profile of HIV-1 specific CD8 T cells and epitope variability with the selection of escape mutants in acute HIV-1 infection. PLoS Pathog, 7 (2), pp. e1001273. | Show Abstract | Read more

In the present study, we analyzed the functional profile of CD8+ T-cell responses directed against autologous transmitted/founder HIV-1 isolates during acute and early infection, and examined whether multifunctionality is required for selection of virus escape mutations. Seven anti-retroviral therapy-naïve subjects were studied in detail between 1 and 87 weeks following onset of symptoms of acute HIV-1 infection. Synthetic peptides representing the autologous transmitted/founder HIV-1 sequences were used in multiparameter flow cytometry assays to determine the functionality of HIV-1-specific CD8+ T memory cells. In all seven patients, the earliest T cell responses were predominantly oligofunctional, although the relative contribution of multifunctional cell responses increased significantly with time from infection. Interestingly, only the magnitude of the total and not of the poly-functional T-cell responses was significantly associated with the selection of escape mutants. However, the high contribution of MIP-1β-producing CD8+ T-cells to the total response suggests that mechanisms not limited to cytotoxicity could be exerting immune pressure during acute infection. Lastly, we show that epitope entropy, reflecting the capacity of the epitope to tolerate mutational change and defined as the diversity of epitope sequences at the population level, was also correlated with rate of emergence of escape mutants.

Salazar-Gonzalez JF, Salazar MG, Learn GH, Fouda GG, Kang HH, Mahlokozera T, Wilks AB, Lovingood RV, Stacey A, Kalilani L et al. 2011. Origin and evolution of HIV-1 in breast milk determined by single-genome amplification and sequencing. J Virol, 85 (6), pp. 2751-2763. | Show Abstract | Read more

HIV transmission via breastfeeding accounts for a considerable proportion of infant HIV acquisition. However, the origin and evolution of the virus population in breast milk, the likely reservoir of transmitted virus variants, are not well characterized. In this study, HIV envelope (env) genes were sequenced from virus variants amplified by single-genome amplification from plasmas and milk of 12 chronically HIV-infected, lactating Malawian women. Maximum likelihood trees and statistical tests of compartmentalization revealed interspersion of plasma and milk HIV env sequences in the majority of subjects, indicating limited or no compartmentalization of milk virus variants. However, phylogenetic tree analysis further revealed monotypic virus variants that were significantly more frequent in milk (median proportion of identical viruses, 29.5%; range, 0 to 61%) than in plasma (median proportion of identical viruses, 0%; range, 0 to 26%) (P = 0.002), suggesting local virus replication in the breast milk compartment. Moreover, clonally amplified virus env genes in milk produced functional virus Envs that were all CCR5 tropic. Milk and plasma virus Envs had similar predicted phenotypes and neutralization sensitivities to broadly neutralizing antibodies in both transmitting and nontransmitting mothers. Finally, phylogenetic comparison of longitudinal milk and plasma virus env sequences revealed synchronous virus evolution and new clonal amplification of evolved virus env genes in milk. The limited compartmentalization and the clonal amplification of evolving, functional viruses in milk indicate continual seeding of the mammary gland by blood virus variants, followed by transient local replication of these variants in the breast milk compartment.

Borrow P, Martínez-Sobrido L, de la Torre JC. 2010. Inhibition of the type I interferon antiviral response during arenavirus infection. Viruses, 2 (11), pp. 2443-2480. | Show Abstract | Read more

Arenaviruses merit interest both as tractable experimental model systems to study acute and persistent viral infections, and as clinically-important human pathogens. Several arenaviruses cause hemorrhagic fever (HF) disease in humans. In addition, evidence indicates that the globally-distributed prototypic arenavirus lymphocytic choriomeningitis virus (LCMV) is a human pathogen of clinical significance in congenital infections, and also poses a great danger to immunosuppressed individuals. Arenavirus persistence and pathogenesis are facilitated by their ability to overcome the host innate immune response. Mammalian hosts have developed both membrane toll-like receptors (TLR) and cytoplasmic pattern recognition receptors (PRRs) that recognize specific pathogen-associated molecular patterns (PAMPs), resulting in activation of the transcription factors IRF3 or IRF7, or both, which together with NF-κB and ATF-2/c-JUN induce production of type I interferon (IFN-I). IFN-I plays a key role in host anti-microbial defense by mediating direct antiviral effects via up-regulation of IFN-I stimulated genes (ISGs), activating dendritic cells (DCs) and natural killer (NK) cells, and promoting the induction of adaptive responses. Accordingly, viruses have developed a plethora of strategies to disrupt the IFN-I mediated antiviral defenses of the host, and the viral gene products responsible for these disruptions are often major virulence determinants. IRF3- and IRF7-dependent induction of host innate immune responses is frequently targeted by viruses. Thus, the arenavirus nucleoprotein (NP) was shown to inhibit the IFN-I response by interfering with the activation of IRF3. This NP anti-IFN activity, together with alterations in the number and function of DCs observed in mice chronically infected with LCMV, likely play an important role in LCMV persistence in its murine host. In this review we will discuss current knowledge about the cellular and molecular mechanisms by which arenaviruses can subvert the host innate immune response and their implications for understanding HF arenaviral disease as well as arenavirus persistence in their natural hosts.

Borrow P, Shattock RJ, Vyakarnam A, EUROPRISE Working Group. 2010. Innate immunity against HIV: a priority target for HIV prevention research. Retrovirology, 7 (1), pp. 84. | Show Abstract | Read more

This review summarizes recent advances and current gaps in understanding of innate immunity to human immunodeficiency virus (HIV) infection, and identifies key scientific priorities to enable application of this knowledge to the development of novel prevention strategies (vaccines and microbicides). It builds on productive discussion and new data arising out of a workshop on innate immunity against HIV held at the European Commission in Brussels, together with recent observations from the literature.Increasing evidence suggests that innate responses are key determinants of the outcome of HIV infection, influencing critical events in the earliest stages of infection including the efficiency of mucosal HIV transmission, establishment of initial foci of infection and local virus replication/spread as well as virus dissemination, the ensuing acute burst of viral replication, and the persisting viral load established. They also impact on the subsequent level of ongoing viral replication and rate of disease progression. Modulation of innate immunity thus has the potential to constitute a powerful effector strategy to complement traditional approaches to HIV prophylaxis and therapy. Importantly, there is increasing evidence to suggest that many arms of the innate response play both protective and pathogenic roles in HIV infection. Consequently, understanding the contributions made by components of the host innate response to HIV acquisition/spread versus control is a critical pre-requisite for the employment of innate immunity in vaccine or microbicide design, so that appropriate responses can be targeted for up- or down-modulation. There is also an important need to understand the mechanisms via which innate responses are triggered and mediate their activity, and to define the structure-function relationships of individual innate factors, so that they can be selectively exploited or inhibited. Finally, strategies for achieving modulation of innate functions need to be developed and subjected to rigorous testing to ensure that they achieve the desired level of protection without stimulation of immunopathological effects. Priority areas are identified where there are opportunities to accelerate the translation of recent gains in understanding of innate immunity into the design of improved or novel vaccine and microbicide strategies against HIV infection.

Sabado RL, O'Brien M, Subedi A, Qin L, Hu N, Taylor E, Dibben O, Stacey A, Fellay J, Shianna KV et al. 2010. Evidence of dysregulation of dendritic cells in primary HIV infection. Blood, 116 (19), pp. 3839-3852. | Show Abstract | Read more

Myeloid and plasmacytoid dendritic cells (DCs) are important mediators of both innate and adaptive immunity against pathogens such as HIV. During the course of HIV infection, blood DC numbers fall substantially. In the present study, we sought to determine how early in HIV infection the reduction occurs and whether the remaining DC subsets maintain functional capacity. We find that both myeloid DC and plasmacytoid DC levels decline very early during acute HIV infection. Despite the initial reduction in numbers, those DCs that remain in circulation retain their function and are able to stimulate allogeneic T-cell responses, and up-regulate maturation markers plus produce cytokines/chemokines in response to stimulation with TLR7/8 agonists. Notably, DCs from HIV-infected subjects produced significantly higher levels of cytokines/chemokines in response to stimulation with TLR7/8 agonists than DCs from uninfected controls. Further examination of gene expression profiles indicated in vivo activation, either directly or indirectly, of DCs during HIV infection. Taken together, our data demonstrate that despite the reduction in circulating DC numbers, those that remain in the blood display hyperfunctionality and implicates a possible role for DCs in promoting chronic immune activation.

Cella M, Presti R, Vermi W, Lavender K, Turnbull E, Ochsenbauer-Jambor C, Kappes JC, Ferrari G, Kessels L, Williams I et al. 2010. Loss of DNAM-1 contributes to CD8+ T-cell exhaustion in chronic HIV-1 infection. Eur J Immunol, 40 (4), pp. 949-954. | Show Abstract | Read more

The hallmark of chronic viral infections is a progressive exhaustion of antigen-specific CD8(+) T cells that leads to persisting viral replication. It is generally believed that exhaustion is a consequence of the accumulation of multiple inhibitory receptors on CD8(+) T cells that makes them dysfunctional. Here, we show that during human chronic HIV-1 infection, a CD8(+) T-cell positive costimulatory pathway mediated by DNAX-activating molecule-1 is also disrupted. Thus, DNAX-activating molecule-1 downregulation on CD8(+) T cells aggravates the impairment of CTL effector function in chronic HIV-1 infection.

Goonetilleke N, Liu MK, Ganusov V, Giorgi E, Salazar J, Li H, Kirchner J, Turnbull E, Bourne V, Moore S et al. 2010. The Role of T Cell Immunity in the Control of HIV Infection INTERNATIONAL JOURNAL OF INFECTIOUS DISEASES, 14 pp. E19-E20. | Read more

Cited:

48

Scopus

Kramer HB, Lavender KJ, Qin L, Stacey AR, Liu MKP, di Gleria K, Simmons A, Gasper-Smith N, Haynes BF, McMichael AJ et al. 2010. Elevation of intact and proteolytic fragments of acute phase proteins constitutes the earliest systemic antiviral response in HIV-1 infection PLoS Pathogens, 6 (5), pp. 1-12. | Show Abstract | Read more

The earliest immune responses activated in acute human immunodeficiency virus type 1 infection (AHI) exert a critical influence on subsequent virus spread or containment. During this time frame, components of the innate immune system such as macrophages and DCs, NK cells, b-defensins, complement and other anti-microbial factors, which have all been implicated in modulating HIV infection, may play particularly important roles. A proteomics-based screen was performed on a cohort from whom samples were available at time points prior to the earliest positive HIV detection. The ability of selected factors found to be elevated in the plasma during AHI to inhibit HIV-1 replication was analyzed using in vitro PBMC and DC infection models. Analysis of unique plasma donor panels spanning the eclipse and viral expansion phases revealed very early alterations in plasma proteins in AHI. Induction of acute phase protein serum amyloid A (A-SAA) occurred as early as 5-7 days prior to the first detection of plasma viral RNA, considerably prior to any elevation in systemic cytokine levels. Furthermore, a proteolytic fragment of alpha-1-antitrypsin (AAT), termed virus inhibitory peptide (VIRIP), was observed in plasma coincident with viremia. Both A-SAA and VIRIP have anti-viral activity in vitro and quantitation of their plasma levels indicated that circulating concentrations are likely to be within the range of their inhibitory activity. Our results provide evidence for a first wave of host anti-viral defense occurring in the eclipse phase of AHI prior to systemic activation of other immune responses. Insights gained into the mechanism of action of acute-phase reactants and other innate molecules against HIV and how they are induced could be exploited for the future development of more efficient prophylactic vaccine strategies. © 2010 Kramer et al.

McMichael AJ, Borrow P, Tomaras GD, Goonetilleke N, Haynes BF. 2010. The immune response during acute HIV-1 infection: clues for vaccine development. Nat Rev Immunol, 10 (1), pp. 11-23. | Show Abstract | Read more

The early immune response to HIV-1 infection is likely to be an important factor in determining the clinical course of disease. Recent data indicate that the HIV-1 quasispecies that arise following a mucosal infection are usually derived from a single transmitted virus. Moreover, the finding that the first effective immune responses drive the selection of virus escape mutations provides insight into the earliest immune responses against the transmitted virus and their contributions to the control of acute viraemia. Strong innate and adaptive immune responses occur subsequently but they are too late to eliminate the infection. In this Review, we discuss recent studies on the kinetics and quality of early immune responses to HIV-1 and their implications for developing a successful preventive HIV-1 vaccine.

Kramer HB, Lavender KJ, Qin L, Stacey AR, Liu MK, di Gleria K, Simmons A, Gasper-Smith N, Haynes BF, McMichael AJ et al. 2010. Elevation of intact and proteolytic fragments of acute phase proteins constitutes the earliest systemic antiviral response in HIV-1 infection. PLoS Pathog, 6 (5), pp. e1000893. | Show Abstract | Read more

The earliest immune responses activated in acute human immunodeficiency virus type 1 infection (AHI) exert a critical influence on subsequent virus spread or containment. During this time frame, components of the innate immune system such as macrophages and DCs, NK cells, beta-defensins, complement and other anti-microbial factors, which have all been implicated in modulating HIV infection, may play particularly important roles. A proteomics-based screen was performed on a cohort from whom samples were available at time points prior to the earliest positive HIV detection. The ability of selected factors found to be elevated in the plasma during AHI to inhibit HIV-1 replication was analyzed using in vitro PBMC and DC infection models. Analysis of unique plasma donor panels spanning the eclipse and viral expansion phases revealed very early alterations in plasma proteins in AHI. Induction of acute phase protein serum amyloid A (A-SAA) occurred as early as 5-7 days prior to the first detection of plasma viral RNA, considerably prior to any elevation in systemic cytokine levels. Furthermore, a proteolytic fragment of alpha-1-antitrypsin (AAT), termed virus inhibitory peptide (VIRIP), was observed in plasma coincident with viremia. Both A-SAA and VIRIP have anti-viral activity in vitro and quantitation of their plasma levels indicated that circulating concentrations are likely to be within the range of their inhibitory activity. Our results provide evidence for a first wave of host anti-viral defense occurring in the eclipse phase of AHI prior to systemic activation of other immune responses. Insights gained into the mechanism of action of acute-phase reactants and other innate molecules against HIV and how they are induced could be exploited for the future development of more efficient prophylactic vaccine strategies.

Fischer W, Ganusov VV, Giorgi EE, Hraber PT, Keele BF, Leitner T, Han CS, Gleasner CD, Green L, Lo CC et al. 2010. Transmission of single HIV-1 genomes and dynamics of early immune escape revealed by ultra-deep sequencing. PLoS One, 5 (8), pp. e12303. | Show Abstract | Read more

We used ultra-deep sequencing to obtain tens of thousands of HIV-1 sequences from regions targeted by CD8+ T lymphocytes from longitudinal samples from three acutely infected subjects, and modeled viral evolution during the critical first weeks of infection. Previous studies suggested that a single virus established productive infection, but these conclusions were tempered because of limited sampling; now, we have greatly increased our confidence in this observation through modeling the observed earliest sample diversity based on vastly more extensive sampling. Conventional sequencing of HIV-1 from acute/early infection has shown different patterns of escape at different epitopes; we investigated the earliest escapes in exquisite detail. Over 3-6 weeks, ultradeep sequencing revealed that the virus explored an extraordinary array of potential escape routes in the process of evading the earliest CD8 T-lymphocyte responses--using 454 sequencing, we identified over 50 variant forms of each targeted epitope during early immune escape, while only 2-7 variants were detected in the same samples via conventional sequencing. In contrast to the diversity seen within epitopes, non-epitope regions, including the Envelope V3 region, which was sequenced as a control in each subject, displayed very low levels of variation. In early infection, in the regions sequenced, the consensus forms did not have a fitness advantage large enough to trigger reversion to consensus amino acids in the absence of immune pressure. In one subject, a genetic bottleneck was observed, with extensive diversity at the second time point narrowing to two dominant escape forms by the third time point, all within two months of infection. Traces of immune escape were observed in the earliest samples, suggesting that immune pressure is present and effective earlier than previously reported; quantifying the loss rate of the founder virus suggests a direct role for CD8 T-lymphocyte responses in viral containment after peak viremia. Dramatic shifts in the frequencies of epitope variants during the first weeks of infection revealed a complex interplay between viral fitness and immune escape.

Anderson JA, Ping LH, Dibben O, Jabara CB, Arney L, Kincer L, Tang Y, Hobbs M, Hoffman I, Kazembe P et al. 2010. HIV-1 Populations in Semen Arise through Multiple Mechanisms. PLoS Pathog, 6 (8), pp. e1001053. | Show Abstract | Read more

HIV-1 is present in anatomical compartments and bodily fluids. Most transmissions occur through sexual acts, making virus in semen the proximal source in male donors. We find three distinct relationships in comparing viral RNA populations between blood and semen in men with chronic HIV-1 infection, and we propose that the viral populations in semen arise by multiple mechanisms including: direct import of virus, oligoclonal amplification within the seminal tract, or compartmentalization. In addition, we find significant enrichment of six out of nineteen cytokines and chemokines in semen of both HIV-infected and uninfected men, and another seven further enriched in infected individuals. The enrichment of cytokines involved in innate immunity in the seminal tract, complemented with chemokines in infected men, creates an environment conducive to T cell activation and viral replication. These studies define different relationships between virus in blood and semen that can significantly alter the composition of the viral population at the source that is most proximal to the transmitted virus.

Munitic I, Decaluwe H, Evaristo C, Lemos S, Wlodarczyk M, Worth A, Le Bon A, Selin LK, Rivière Y, Di Santo JP et al. 2009. Epitope specificity and relative clonal abundance do not affect CD8 differentiation patterns during lymphocytic choriomeningitis virus infection. J Virol, 83 (22), pp. 11795-11807. | Show Abstract | Read more

To evaluate the impact of immunodominance on CD8 T-cell properties, we compared the functional properties of dominant and subdominant populations in the response to lymphocytic choriomeningitis virus (LCMV). To improve functional discrimination, in addition to the usual tests of phenotype and function, we used a sensitive technique that allows the screening of all CD8 effector genes simultaneously in single cells. Surprisingly, these methods failed to reveal a major impact of clonal dominance in CD8 properties throughout the response. Aiming to increase clonal dominance, we examined high-frequency transferred P14 T-cell receptor transgenic (TCR Tg) cells. Under these conditions LCMV is cleared faster, and accordingly we found an accelerated response. However, when Tg and endogenous cells were studied in the same mice, where they should be subjected to the same antigen load, they showed overlapping properties, and the presence of P14 cells did not modify endogenous responses to other LCMV epitopes or a perturbed immunodominance hierarchy in the memory phase. Using allotype-labeled Tg cells, we found that during acute infection up to 80% downregulated their TCR and were undetectable by tetramer binding, and that tetramer-negative and tetramer-positive cells had very different features. Since Tg cells are not available to evaluate immune responses in humans and, in many cases, are not available from the mouse, the tetramer-based evaluation of early immune responses in most situations of high viremia may be incomplete and biased.

Yang H, Guimarães-Walker A, Hibbs S, Dong T, Stacey A, Borrow P, Hanke T, Davenport MP, McMichael A, Dorrell L. 2009. Interleukin-10 responses to therapeutic vaccination during highly active antiretroviral therapy and after analytical therapy interruption. AIDS, 23 (16), pp. 2226-2230. | Show Abstract | Read more

We investigated whether therapeutic vaccination in highly active antiretroviral therapy (HAART)-treated patients with a modified vaccinia virus Ankara-vectored HIV-1 vaccine, with or without therapy interruption, induced the production of interleukin (IL)-10. Plasma IL-10 levels were not significantly increased postvaccination, but increased in parallel with viraemia in patients who interrupted therapy. Surprisingly, IL-10 blockade augmented HIV-specific T cell proliferative responses in HAART-suppressed patients but had no effect once virological control was lost. Modulation of IL-10 might enhance vaccine-induced immune responses.

Goonetilleke N, Liu MK, Salazar-Gonzalez JF, Ferrari G, Giorgi E, Ganusov VV, Keele BF, Learn GH, Turnbull EL, Salazar MG et al. 2009. The first T cell response to transmitted/founder virus contributes to the control of acute viremia in HIV-1 infection. J Exp Med, 206 (6), pp. 1253-1272. | Show Abstract | Read more

Identification of the transmitted/founder virus makes possible, for the first time, a genome-wide analysis of host immune responses against the infecting HIV-1 proteome. A complete dissection was made of the primary HIV-1-specific T cell response induced in three acutely infected patients. Cellular assays, together with new algorithms which identify sites of positive selection in the virus genome, showed that primary HIV-1-specific T cells rapidly select escape mutations concurrent with falling virus load in acute infection. Kinetic analysis and mathematical modeling of virus immune escape showed that the contribution of CD8 T cell-mediated killing of productively infected cells was earlier and much greater than previously recognized and that it contributed to the initial decline of plasma virus in acute infection. After virus escape, these first T cell responses often rapidly waned, leaving or being succeeded by T cell responses to epitopes which escaped more slowly or were invariant. These latter responses are likely to be important in maintaining the already established virus set point. In addition to mutations selected by T cells, there were other selected regions that accrued mutations more gradually but were not associated with a T cell response. These included clusters of mutations in envelope that were targeted by NAbs, a few isolated sites that reverted to the consensus sequence, and bystander mutations in linkage with T cell-driven escape.

Turnbull EL, Wong M, Wang S, Wei X, Jones NA, Conrod KE, Aldam D, Turner J, Pellegrino P, Keele BF et al. 2009. Kinetics of expansion of epitope-specific T cell responses during primary HIV-1 infection. J Immunol, 182 (11), pp. 7131-7145. | Show Abstract | Read more

Multiple lines of evidence support a role for CD8(+) T cells in control of acute/early HIV replication; however, features of the primary HIV-specific CD8(+) T cell response that may impact on the efficiency of containment of early viral replication remain poorly defined. In this study, we performed a novel, comprehensive analysis of the kinetics of expansion of components of the HIV-specific CD8(+) T cell response in 21 acutely infected individuals. Epitope-specific T cell responses expanded asynchronously during primary infection in all subjects. The most rapidly expanded responses peaked as early as 5 days following symptomatic presentation and were typically of very limited epitope breadth. Responses of additional specificities expanded and contracted in subsequent waves, resulting in successive shifts in the epitope immunodominance hierarchy over time. Sequence variation and escape were temporally associated with the decline in magnitude of only a subset of T cell responses, suggesting that other factors such as Ag load and T cell exhaustion may play a role in driving the contraction of HIV-specific T cell responses. These observations document the preferential expansion of CD8(+) T cells recognizing a subset of epitopes during the viral burst in acute HIV-1 infection and suggest that the nature of the initial, very rapidly expanded T cell response may influence the efficiency with which viral replication is contained in acute/early HIV infection.

Lee LN, Burke S, Montoya M, Borrow P. 2009. Multiple mechanisms contribute to impairment of type 1 interferon production during chronic lymphocytic choriomeningitis virus infection of mice. J Immunol, 182 (11), pp. 7178-7189. | Show Abstract | Read more

Type 1 IFNs, innate cytokines with important effector and immunomodulatory properties, are rapidly induced in the acute phase of many virus infections; however, this is generally a transient response that is not sustained during virus persistence. To gain insight into mechanisms that can contribute to down-regulation of type 1 IFN production during virus persistence, we analyzed type 1 IFN production during acute and chronic lymphocytic choriomeningitis virus (LCMV) infection. High-level type 1 IFN production was transiently up-regulated in cells including plasmacytoid and conventional dendritic cells (DCs) following LCMV infection of mice, but LCMV persistence was associated with only low-level type 1 IFN production. Nonetheless, chronically infected mice were able to up-regulate type 1 IFN production in response to TLR3, 7, and 9 ligands, albeit less efficiently than uninfected mice. Splenic DC numbers in mice chronically infected with LCMV were decreased, and the remaining cells exhibited a reduced response to TLR stimulation. LCMV-infected cell lines efficiently up-regulated type 1 IFN production following TLR ligation and infection with a DNA virus, but exhibited a defect in type 1 IFN induction following infection with Sendai, an RNA virus. This block in type 1 IFN production by infected cells, together with abnormalities in DC numbers and functions, likely contribute to the low-level type 1 IFN production in mice chronically infected with LCMV. Impairment of type 1 IFN production may both promote virus persistence and impact on host immunocompetence. Understanding the mechanisms involved may assist in development of strategies for control of virus persistence and superinfection.

Stacey AR, Norris PJ, Qin L, Haygreen EA, Taylor E, Heitman J, Lebedeva M, DeCamp A, Li D, Grove D et al. 2009. Induction of a striking systemic cytokine cascade prior to peak viremia in acute human immunodeficiency virus type 1 infection, in contrast to more modest and delayed responses in acute hepatitis B and C virus infections. J Virol, 83 (8), pp. 3719-3733. | Show Abstract | Read more

Characterization of the immune responses induced in the initial stages of human immunodeficiency virus type 1 (HIV-1) infection is of critical importance for an understanding of early viral pathogenesis and prophylactic vaccine design. Here, we used sequential plasma samples collected during the eclipse and exponential viral expansion phases from subjects acquiring HIV-1 (or, for comparison, hepatitis B virus [HBV]or hepatitis C virus [HCV]) to determine the nature and kinetics of the earliest systemic elevations in cytokine and chemokine levels in each infection. Plasma viremia was quantitated over time, and levels of 30 cytokines and chemokines were measured using Luminex-based multiplex assays and enzyme-linked immunosorbent assays. The increase in plasma viremia in acute HIV-1 infection was found to be associated with elevations in plasma levels of multiple cytokines and chemokines, including rapid and transient elevations in alpha interferon (IFN-alpha) and interleukin-15 (IL-15) levels; a large increase in inducible protein 10 (IP-10) levels; rapid and more-sustained increases in tumor necrosis factor alpha and monocyte chemotactic protein 1 levels; more slowly initiated elevations in levels of additional proinflammatory factors including IL-6, IL-8, IL-18, and IFN-gamma; and a late-peaking increase in levels of the immunoregulatory cytokine IL-10. Notably, there was comparatively little perturbation in plasma cytokine levels during the same phase of HBV infection and a delayed response of more intermediate magnitude in acute HCV infection, indicating that the rapid activation of a striking systemic cytokine cascade is not a prerequisite for viral clearance (which occurs in a majority of HBV-infected individuals). The intense early cytokine storm in acute HIV-1 infection may have immunopathological consequences, promoting immune activation, viral replication, and CD4(+) T-cell loss.

Stacey A, Norris P, Dibben O, Qin L, Cohen M, Gay C, Denny T, Borrow P. 2009. Striking elevations in systemic and mucosal cytokine and chemokine levels in acute HIV-1 infection RETROVIROLOGY, 6 (SUPPL. 3),

Liu MK, Ferrari G, Salazar J, Keele B, Tanner RL, Hraber P, Giorgi E, Ganusov VV, Learn GH, Salazar MG et al. 2009. The role of early T-cell responses in subjects with acute HIV-1 infection RETROVIROLOGY, 6 (SUPPL. 3),

Dibben O, Assa-Chapman M, Lewis J, McKnight A, Williams I, Borrow P. 2009. Investigation of the sensitivity of acute-phase HIV-1 isolates to type I interferons RETROVIROLOGY, 6 (SUPPL. 3),

Brackenridge S, Corrah T, Haygreen E, Lavender K, Dong T, Goonetilleke N, Borrow P, McMichael A. 2009. Does increased expression of HLA-C allow better control of HIV-1 viral load? RETROVIROLOGY, 6 (Suppl 3), pp. P113-P113. | Read more

Qin L, Stacey A, Norris P, Wang P, Borrow P, Self SG. 2009. Dynamic profiling and correlation analysis of plasma viral load and cytokine and chemokine profiles in acute HIV-1 infection RETROVIROLOGY, 6 (Suppl 3), pp. P145-P145. | Read more

Walshe VA, Hattotuwagama CK, Doytchinova IA, Wong M, Macdonald IK, Mulder A, Claas FH, Pellegrino P, Turner J, Williams I et al. 2009. Integrating in silico and in vitro analysis of peptide binding affinity to HLA-Cw*0102: a bioinformatic approach to the prediction of new epitopes. PLoS One, 4 (11), pp. e8095. | Show Abstract | Read more

BACKGROUND: Predictive models of peptide-Major Histocompatibility Complex (MHC) binding affinity are important components of modern computational immunovaccinology. Here, we describe the development and deployment of a reliable peptide-binding prediction method for a previously poorly-characterized human MHC class I allele, HLA-Cw*0102. METHODOLOGY/FINDINGS: Using an in-house, flow cytometry-based MHC stabilization assay we generated novel peptide binding data, from which we derived a precise two-dimensional quantitative structure-activity relationship (2D-QSAR) binding model. This allowed us to explore the peptide specificity of HLA-Cw*0102 molecule in detail. We used this model to design peptides optimized for HLA-Cw*0102-binding. Experimental analysis showed these peptides to have high binding affinities for the HLA-Cw*0102 molecule. As a functional validation of our approach, we also predicted HLA-Cw*0102-binding peptides within the HIV-1 genome, identifying a set of potent binding peptides. The most affine of these binding peptides was subsequently determined to be an epitope recognized in a subset of HLA-Cw*0102-positive individuals chronically infected with HIV-1. CONCLUSIONS/SIGNIFICANCE: A functionally-validated in silico-in vitro approach to the reliable and efficient prediction of peptide binding to a previously uncharacterized human MHC allele HLA-Cw*0102 was developed. This technique is generally applicable to all T cell epitope identification problems in immunology and vaccinology.

Rizza P, Capone I, Urbani F, Montefiore E, Rapicetta M, Chionne P, Candido A, Tosti ME, Grimaldi M, Palazzini E et al. 2008. Evaluation of the effects of human leukocyte IFN-alpha on the immune response to the HBV vaccine in healthy unvaccinated individuals. Vaccine, 26 (8), pp. 1038-1049. | Show Abstract | Read more

HBV vaccine needs 3 injections over 6 months to induce immunity. Thus, the use of adjuvants capable of inducing earlier immune protection would be highly desirable. Most adjuvants may act by inducing cytokines, and among them, type I interferons (IFNs), deserve a special attention in view of the potent immunomostimulatory activity observed in mouse models and on dendritic cell functions. The aim of the present trial was to evaluate the effects of IFN-alpha administered as an adjuvant of HBV vaccine in healthy unvaccinated individuals. No significant enhancing effect on the antibody response was observed, in spite of an early and transient upregulation of costimulatory molecule expression on peripheral blood mononuclear cells, which may be suggestive of an IFN-mediated activation of antigen presenting cells. We conclude that, under the conditions used in this trial, natural IFN-alpha does not act as an adjuvant of the HBV vaccine in healthy unvaccinated individuals.

Borrow P, Bhardwaj N. 2008. Innate immune responses in primary HIV-1 infection. Curr Opin HIV AIDS, 3 (1), pp. 36-44. | Show Abstract | Read more

PURPOSE OF REVIEW: Events occurring in acute HIV-1 infection are now recognized to be critical determinants of the subsequent disease course. Innate responses constitute the first line of defence against pathogens, and also play a key role in triggering the early adaptive response; as such, the innate responses activated in acute HIV-1 infection and their contribution to control of viral replication or disease pathogenesis are the focus of much current research. We review recent advances in this area. RECENT FINDINGS: Dendritic cell subsets can play pleiotropic roles in acute HIV-1 infection, with in-vitro studies illustrating that HIV-dendritic cell interactions may have outcomes as diverse as virion destruction, virus dissemination, T-cell triggering or subversion of dendritic cell functions. Natural killer cells can be activated in acute HIV-1 infection, and mounting evidence suggests that they contribute to determining the ensuing course of disease; however, much remains to be learned about how they mediate their effects. SUMMARY: The importance of innate responses as determinants of the outcome of HIV infection is increasingly evident, but more work is needed to understand how innate immunity can be harnessed to combat this infection.

Owen RE, Yamada E, Thompson CI, Phillipson LJ, Thompson C, Taylor E, Zambon M, Osborn HM, Barclay WS, Borrow P. 2007. Alterations in receptor binding properties of recent human influenza H3N2 viruses are associated with reduced natural killer cell lysis of infected cells. J Virol, 81 (20), pp. 11170-11178. | Show Abstract | Read more

Natural killer (NK) cell recognition of influenza virus-infected cells involves hemagglutinin (HA) binding to sialic acid (SA) on activating NK receptors. SA also acts as a receptor for the binding of influenza virus to its target host cells. The SA binding properties of H3N2 influenza viruses have been observed to change during circulation in humans: recent isolates are unable to agglutinate chicken red blood cells and show reduced affinity for synthetic glycopolymers representing SA-alpha-2,3-lactose (3'SL-PAA) and SA-alpha-2,6-N-acetyl lactosamine (6'SLN-PAA) carbohydrates. Here, NK lysis of cells infected with human H3N2 influenza viruses isolated between 1969 and 2003 was analyzed. Cells infected with recent isolates (1999 to 2003) were found to be lysed less effectively than cells infected with older isolates (1969 to 1996). This change occurred concurrently with the acquisition of two new potential glycosylation site motifs in HA. Deletion of the potential glycosylation site motif at 133 to 135 in HA1 from a recent isolate partially restored the agglutination phenotype to a recombinant virus, indicating that the HA-SA interaction is inhibited by the glycosylation modification. Deletion of either of the recently acquired potential glycosylation sites from HA led to increased NK lysis of cells infected with recombinant viruses carrying modified HA. These results indicate that alterations in HA glycosylation may affect NK cell recognition of influenza virus-infected cells in addition to virus binding to host cells.

Marshall-Clarke S, Downes JE, Haga IR, Bowie AG, Borrow P, Pennock JL, Grencis RK, Rothwell P. 2007. Polyinosinic acid is a ligand for toll-like receptor 3. J Biol Chem, 282 (34), pp. 24759-24766. | Show Abstract | Read more

Innate immune responses are critical in controlling viral infections. Viral proteins and nucleic acids have been shown to be recognized by pattern recognition receptors of the Toll-like receptor (TLR) family, triggering downstream signaling cascades that lead to cellular activation and cytokine production. Viral DNA is sensed by TLR9, and TLRs 3, 7, and 8 have been implicated in innate responses to RNA viruses by virtue of their ability to sense double-stranded (ds) RNA (TLR3) or single-stranded RNA (murine TLR7 and human TLR8). Viral and synthetic dsRNAs have also been shown to be a potent adjuvant, promoting enhanced adaptive immune responses, and this property is also dependent on their recognition by TLR3. It has recently been shown that mRNA that is largely single-stranded is a ligand for TLR3. Here we have investigated the ability of single-stranded homopolymeric nucleic acids to induce innate responses by murine immune cells. We show for the first time that polyinosinic acid (poly(I)) activates B lymphocytes, dendritic cells, and macrophages and that these responses are dependent on the expression of both TLR3 and the adaptor molecule, Toll/IL-1 receptor domain-containing adaptor inducing IFN-beta (TRIF). We therefore conclude that TLR3 is able to sense both single-stranded RNA and dsRNA.

Yang H, Dong T, Turnbull E, Ranasinghe S, Ondondo B, Goonetilleke N, Winstone N, di Gleria K, Bowness P, Conlon C et al. 2007. Broad TCR usage in functional HIV-1-specific CD8+ T cell expansions driven by vaccination during highly active antiretroviral therapy. J Immunol, 179 (1), pp. 597-606. | Show Abstract

During chronic HIV-1 infection, continuing viral replication is associated with impaired proliferative capacity of virus-specific CD8+ T cells and with the expansion and persistence of oligoclonal T cell populations. TCR usage may significantly influence CD8+ T cell-mediated control of AIDS viruses; however, the potential to modulate the repertoire of functional virus-specific T cells by immunotherapy has not been explored. To investigate this, we analyzed the TCR Vbeta usage of CD8+ T cells populations which were expanded following vaccination with modified vaccinia virus Ankara expressing a HIV-1 gag/multiepitope immunogen (MVA.HIVA) in HIV-1-infected patients receiving highly active antiretroviral therapy. Vaccinations induced the re-expansion of HIV-1-specific CD8+ T cells and these showed broad TCR Vbeta usage which was maintained for at least 1 year in some individuals. By contrast, virus-specific CD8+ T cell populations in the same donors which failed to expand after vaccination and in unvaccinated controls were oligoclonal. Simultaneously, we observed that CD8+ T cells recognizing vaccine-derived HIV-1 epitopes displayed enhanced capacity to proliferate and to inhibit HIV-1 replication in vitro, following MVA.HIVA immunizations. Taken together, these data indicate that an attenuated viral-vectored vaccine can modulate adaptive CD8+ T cell responses to HIV-1 and improve their antiviral functional capacity. The potential therapeutic benefit of this vaccination approach warrants further investigation.

Dunn C, Brunetto M, Reynolds G, Christophides T, Kennedy PT, Lampertico P, Das A, Lopes AR, Borrow P, Williams K et al. 2007. Cytokines induced during chronic hepatitis B virus infection promote a pathway for NK cell-mediated liver damage. J Exp Med, 204 (3), pp. 667-680. | Show Abstract | Read more

Hepatitis B virus (HBV) causes chronic infection in more than 350 million people worldwide. It replicates in hepatocytes but is non-cytopathic; liver damage is thought to be immune mediated. Here, we investigated the role of innate immune responses in mediating liver damage in patients with chronic HBV infection. Longitudinal analysis revealed a temporal correlation between flares of liver inflammation and fluctuations in interleukin (IL)-8, interferon (IFN)-alpha, and natural killer (NK) cell expression of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) directly ex vivo. A cross-sectional study confirmed these findings in patients with HBV-related liver inflammation compared with healthy carriers. Activated, TRAIL-expressing NK cells were further enriched in the liver of patients with chronic HBV infection, while their hepatocytes expressed increased levels of a TRAIL death-inducing receptor. IFN-alpha concentrations found in patients were capable of activating NK cells to induce TRAIL-mediated hepatocyte apoptosis in vitro. The pathogenic potential of this pathway could be further enhanced by the ability of the IFN-alpha/IL-8 combination to dysregulate the balance of death-inducing and regulatory TRAIL receptors expressed on hepatocytes. We conclude that NK cells may contribute to liver inflammation by TRAIL-mediated death of hepatocytes and demonstrate that this non-antigen-specific mechanism can be switched on by cytokines produced during active HBV infection.

Le Bon A, Montoya M, Edwards MJ, Thompson C, Burke SA, Ashton M, Lo D, Tough DF, Borrow P. 2006. A role for the transcription factor RelB in IFN-alpha production and in IFN-alpha-stimulated cross-priming. Eur J Immunol, 36 (8), pp. 2085-2093. | Show Abstract | Read more

Chimeric mice generated with bone marrow from RelB-deficient (-/-), RelB-heterozygous (+/-) and wild-type (+/+) mice were used to determine how total or partial absence of the transcription factor RelB in haematopoietic cells affects the immune response generated after lymphocytic choriomeningitis virus (LCMV) infection. In RelB(-/-) chimeras, early virus replication was enhanced and LCMV clearance was impaired. Although plasmacytoid dendritic cell numbers were similar, serum interferon (IFN)-alpha levels in RelB(-/-) and RelB(+/-) chimeras were markedly lower than in RelB(+/+) chimeras during early LCMV infection. Further, both RelB(-/-) and RelB(+/-) chimeras mounted a lower-magnitude LCMV-specific CD8(+) T cell response than their RelB(+/+) counterparts, although the LCMV-specific CD8(+) T cells present were differentiated into functional cytotoxic cells. In LCMV-infected RelB(-/-) mice, induction of cross-priming to an independently injected soluble protein, which depends on the IFN-alpha/beta made during the viral infection, was also impaired. Notably, provision of exogenous IFN-alpha did not restore the ability of RelB(-/-) mice to cross-prime. In summary, these results show that the RelB/NF-kappaB pathway is required for optimal IFN-alpha production after LCMV infection and suggest a crucial role for RelB in IFN-alpha-stimulated cross-priming of CD8(+) T cell responses.

Montoya M, Dawes R, Reid D, Lee LN, Piercy J, Borrow P, Tchilian EZ, Beverley PC. 2006. CD45 is required for type I IFN production by dendritic cells. Eur J Immunol, 36 (8), pp. 2150-2158. | Show Abstract | Read more

CD45 is a leukocyte tyrosine phosphatase, essential for normal immune responses. We have studied the function of splenic dendritic cells of CD45(+/+), CD45(-/-), CD45RABC and CD45RO transgenic mice. We show that there are increased numbers of plasmacytoid dendritic cells in CD45(-/-) mice. DC of all mice are capable of responding to lymphocytic choriomeningitis virus (LCMV) infection by up-regulation of MHC and costimulatory molecules. DC of CD45(-/-) mice have an impaired capacity to produce type I interferons in response to LCMV infection in vivo. These data indicate that lack of CD45 expression in DC has a profound effect on their function. This is largely restored by CD45RABC or CD45RO transgenes.

Borrow P, Turnbull EL. 2006. The promise and challenge of anti-HIV cellular immunity. Curr Opin HIV AIDS, 1 (4), pp. 277-285. | Show Abstract | Read more

PURPOSE OF REVIEW: We discuss recent studies giving insight into the promise of cell-mediated immunity for prophylactic HIV vaccine strategies, and challenges to be overcome for this approach to succeed. RECENT FINDINGS: Advances in understanding of events in very early HIV infection and their importance in viral pathogenesis emphasize the rapidity with which vaccine-induced T-cell responses must act to modulate CD4 cell destruction, but also reveal an early window of opportunity when foci of infection are limited and could potentially be eliminated. Super-infection with diverse HIV strains is now appreciated to be relatively common, indicating that cell-mediated responses in most infected individuals do not confer protection. Recent studies suggest that T-cell correlates of good control of HIV replication may be a consequence rather than a cause of containment of viraemia. Analysis of features of HIV-specific T-cell responses restricted by human leukocyte antigen alleles associated with differential prognosis of infection is giving insight into correlates of protection. The importance of efficacious responses, escape from which incurs high fitness costs, is increasingly appreciated. SUMMARY: There are many challenges to be overcome before the promise of cell-mediated immunity for HIV vaccines is realized.

Turnbull EL, Lopes AR, Jones NA, Cornforth D, Newton P, Aldam D, Pellegrino P, Turner J, Williams I, Wilson CM et al. 2006. HIV-1 epitope-specific CD8+ T cell responses strongly associated with delayed disease progression cross-recognize epitope variants efficiently. J Immunol, 176 (10), pp. 6130-6146. | Show Abstract

The ability of HIV-1-specific CD8(+) T cell responses to recognize epitope variants resulting from viral sequence variation in vivo may affect the ease with which HIV-1 can escape T cell control and impact on the rate of disease progression in HIV-1-infected humans. Here, we studied the functional cross-reactivity of CD8 responses to HIV-1 epitopes restricted by HLA class I alleles associated with differential prognosis of infection. We show that the epitope-specific responses exhibiting the most efficient cross-recognition of amino acid-substituted variants were those strongly associated with delayed progression to disease. Not all epitopes restricted by the same HLA class I allele showed similar variant cross-recognition efficiency, consistent with the hypothesis that the reported associations between particular HLA class I alleles and rate of disease progression may be due to the quality of responses to certain "critical" epitopes. Irrespective of their efficiency of functional cross-recognition, CD8(+) T cells of all HIV-1 epitope specificities examined showed focused TCR usage. Furthermore, interpatient variability in variant cross-reactivity correlated well with use of different dominant TCR Vbeta families, suggesting that flexibility is not conferred by the overall clonal breadth of the response but instead by properties of the dominant TCR(s) used for epitope recognition. A better understanding of the features of T cell responses associated with long-term control of viral replication should facilitate rational vaccine design.

Marshall-Clarke S, Tasker L, Buchatska O, Downes J, Pennock J, Wharton S, Borrow P, Wiseman DZ. 2006. Influenza H2 haemagglutinin activates B cells via a MyD88-dependent pathway. Eur J Immunol, 36 (1), pp. 95-106. | Show Abstract | Read more

Influenza viruses are serious respiratory pathogens, responsible for half a million deaths each year. The viral surface haemagglutinin (HA) protein has been shown to be an important determinant of viral pathogenicity. HA is the virion attachment and fusion protein, and the major target for neutralizing antibodies; however, it is also involved in triggering innate responses that may have an important impact on the disease course. We have examined the role of the toll-like receptor (TLR) family in innate responses to influenza virus and influenza HA. TLR7 has recently been found to mediate recognition of influenza RNA. Here, we show for the first time that influenza HA of the H2 subtype induces innate responses in murine B lymphocytes via a MyD88-dependent pathway distinct from that involved in sensing viral RNA. We also show that inactivated influenza virus induces activation of human B cells. Our findings suggest that the molecule mediating these responses may be a novel member of the TLR family.

Guan P, Doytchinova IA, Walshe VA, Borrow P, Flower DR. 2005. Analysis of peptide-protein binding using amino acid descriptors: prediction and experimental verification for human histocompatibility complex HLA-A0201. J Med Chem, 48 (23), pp. 7418-7425. | Show Abstract | Read more

Amino acid descriptors are often used in quantitative structure-activity relationship (QSAR) analysis of proteins and peptides. In the present study, descriptors were used to characterize peptides binding to the human MHC allele HLA-A0201. Two sets of amino acid descriptors were chosen: 93 descriptors taken from the amino acid descriptor database AAindex and the z descriptors defined by Wold and Sandberg. Variable selection techniques (SIMCA, genetic algorithm, and GOLPE) were applied to remove redundant descriptors. Our results indicate that QSAR models generated using five z descriptors had the highest predictivity and explained variance (q2 between 0.6 and 0.7 and r2 between 0.6 and 0.9). Further to the QSAR analysis, 15 peptides were synthesized and tested using a T2 stabilization assay. All peptides bound to HLA-A0201 well, and four peptides were identified as high-affinity binders.

Edwards MJ, Buchatska O, Ashton M, Montoya M, Bickle QD, Borrow P. 2005. Reciprocal immunomodulation in a schistosome and hepatotropic virus coinfection model. J Immunol, 175 (10), pp. 6275-6285. | Show Abstract

Human coinfection with the helminth parasite Schistosoma mansoni and hepatitis B and hepatitis C viruses is associated with increased hepatic viral burdens and severe liver pathology. In this study we developed a murine S. mansoni/lymphocytic choriomeningitis virus (LCMV) coinfection model that reproduces the enhanced viral replication and liver pathology observed in human coinfections, and used this model to explore the mechanisms involved. Viral coinfection during the Th2-dominated granulomatous phase of the schistosome infection resulted in induction of a strong LCMV-specific T cell response, with infiltration of high numbers of LCMV-specific IFN-gamma-producing CD8+ cells into the liver. This was associated with suppression of production of the Th2 cytokines dominant during S. mansoni infection and a rapid increase in morbidity, linked to hepatotoxicity. Interestingly, the liver of coinfected mice was extremely susceptible to viral replication. This correlated with a reduced intrahepatic type I IFN response following virus infection. Schistosome egg Ags were found to suppress the type I IFN response induced in murine bone marrow-derived dendritic cells by polyinosinic-polycytidylic acid. These results suggest that suppression of the antiviral type I IFN response by schistosome egg Ags in vivo predisposes the liver to enhanced viral replication with ensuing immunopathological consequences, findings that may be paralleled in human schistosome/hepatotropic virus coinfections.

Guan P, Davies M, Taylor DJ, Wan S, McSparron HM, Hemsley SL, Toseland C, Blythe MJ, Taylor PD, Walshe V et al. 2005. Computational Chemistry, Informatics, and the Discovery of Vaccines CURRENT COMPUTER-AIDED DRUG DESIGN, 1 (4), pp. 377-395. | Read more

Meier UC, Owen RE, Taylor E, Worth A, Naoumov N, Willberg C, Tang K, Newton P, Pellegrino P, Williams I et al. 2005. Shared alterations in NK cell frequency, phenotype, and function in chronic human immunodeficiency virus and hepatitis C virus infections. J Virol, 79 (19), pp. 12365-12374. | Show Abstract | Read more

Human immunodeficiency virus (HIV) and hepatitis C virus (HCV) cause clinically important persistent infections. The effects of virus persistence on innate immunity, including NK cell responses, and the underlying mechanisms are not fully understood. We examined the frequency, phenotype, and function of peripheral blood CD3- CD56+ NK subsets in HIV+ and HCV+ patients and identified significantly reduced numbers of total NK cells and a striking shift in NK subsets, with a marked decrease in the CD56(dim) cell fraction compared to CD56(bright) cells, in both infections. This shift influenced the phenotype and functional capacity (gamma interferon production, killing) of the total NK pool. In addition, abnormalities in the functional capacity of the CD56(dim) NK subset were observed in HIV+ patients. The shared NK alterations were found to be associated with a significant reduction in serum levels of the innate cytokine interleukin 15 (IL-15). In vitro stimulation with IL-15 rescued NK cells of HIV+ and HCV+ patients from apoptosis and enhanced proliferation and functional activity. We hypothesize that the reduced levels of IL-15 present in the serum during HIV and HCV infections might impact NK cell homeostasis, contributing to the common alterations of the NK pool observed in these unrelated infections.

Yamada E, Montoya M, Schuettler CG, Hickling TP, Tarr AW, Vitelli A, Dubuisson J, Patel AH, Ball JK, Borrow P. 2005. Analysis of the binding of hepatitis C virus genotype 1a and 1b E2 glycoproteins to peripheral blood mononuclear cell subsets. J Gen Virol, 86 (Pt 9), pp. 2507-2512. | Show Abstract | Read more

Hepatitis C virus (HCV) binding to hepatocytes is thought to be mediated via interaction of the E2 glycoprotein with (co-)receptors including CD81 and scavenger receptor class B type I (SR-BI). Here, the expression of CD81 and SR-BI was analysed on peripheral blood mononuclear cell (PBMC) subsets, and the binding of genotype 1 soluble truncated E2 (sE2) proteins to these cells was investigated. All PBMC subsets expressed CD81, although at varying levels. In contrast, SR-BI was only detected on monocytes and dendritic cells (DCs). The genotype 1a H77c sE2 protein showed higher PBMC binding than other genotype 1a/b sE2s. H77c sE2 binding to different PBMC subsets largely paralleled their level of CD81 expression, and could be inhibited by blocking E2-CD81 interaction. However, those PBMC subsets reported to be infected by HCV in vivo (monocytes, DCs and B cells) also exhibited residual, CD81-independent binding, indicating roles for SR-BI/other receptor(s) in mediating haematopoietic cell infection.

Marzo AL, Klonowski KD, Le Bon A, Borrow P, Tough DF, Lefrançois L. 2005. Initial T cell frequency dictates memory CD8+ T cell lineage commitment. Nat Immunol, 6 (8), pp. 793-799. | Show Abstract | Read more

Memory T cells can be divided into central memory T cell (T(CM) cell) and effector memory T cell (T(EM) cell) subsets based on homing characteristics and effector functions. Whether T(EM) and T(CM) cells represent interconnected or distinct lineages is unclear, although the present paradigm suggests that T(EM) and T(CM) cells follow a linear differentiation pathway from naive T cells to effector T cells to T(EM) cells to T(CM) cells. We show here that naive T cell precursor frequency profoundly influenced the pathway along which CD8+ memory T cells developed. At low precursor frequency, those T(EM) cells generated represented a stable cell lineage that failed to further differentiate into T(CM) cells. These findings do not adhere to the present dogma regarding memory T cell generation and provide a means for identifying factors controlling memory T cell lineage commitment.

Brown RJ, Juttla VS, Tarr AW, Finnis R, Irving WL, Hemsley S, Flower DR, Borrow P, Ball JK. 2005. Evolutionary dynamics of hepatitis C virus envelope genes during chronic infection. J Gen Virol, 86 (Pt 7), pp. 1931-1942. | Show Abstract | Read more

Hepatitis C virus (HCV) envelope glycoproteins E1 and E2 are important targets for the host immune response. The genes encoding these proteins exhibit a high degree of variability that gives rise to differing phenotypic traits, including alterations in receptor-binding affinity and immune recognition and escape. In order to elucidate patterns of adaptive evolution during chronic infection, a panel of full-length E1E2 clones was generated from sequential serum samples obtained from four chronically infected individuals. By using likelihood-based methods for phylogenetic inference, the evolutionary dynamics of circulating HCV quasispecies populations were assessed and a site-by-site analysis of the d(N)/d(S) ratio was performed, to identify specific codons undergoing diversifying positive selection. HCV phylogenies, coupled with the number and distribution of selected sites, differed markedly between patients, highlighting that HCV evolution during chronic infection is a patient-specific phenomenon. This analysis shows that purifying selection is the major force acting on HCV populations in chronic infection. Whilst no significant evidence for positive selection was observed in E1, a number of sites under positive selection were identified within the ectodomain of the E2 protein. All of these sites were located in regions hypothesized to be exposed to the selective environment of the host, including a number of functionally defined domains that have been reported to be involved in immune evasion and receptor binding. Dated-tip methods for estimation of underlying HCV mutation rates were also applied to the data, enabling prediction of the most recent common ancestor for each patient's quasispecies.

Morra M, Barrington RA, Abadia-Molina AC, Okamoto S, Julien A, Gullo C, Kalsy A, Edwards MJ, Chen G, Spolski R et al. 2005. Defective B cell responses in the absence of SH2D1A. Proc Natl Acad Sci U S A, 102 (13), pp. 4819-4823. | Show Abstract | Read more

More than half of patients with X-linked lympho-proliferative disease, which is caused by a defect in the intracellular adapter protein SH2D1A, suffer from an extreme susceptibility to Epstein-Barr virus. One-third of these patients, however, develop dysgammaglobulenemia without an episode of severe mononucleosis. Here we show that in SH2D1A(-/-) mice, both primary and secondary responses of all Ig subclasses are severely impaired in response to specific antigens. Because germinal centers were absent in SH2D1A(-/-) mice upon primary immunization, and because SH2D1A was detectable in wt germinal center B cells, we examined whether SH2D1A(-/-) B cell functions were impaired. Using the adoptive cotransfer of B lymphocytes from hapten-primed SH2D1A(-/-) mice with CD4(+) T cells from primed wt mice into irradiated wt mice provided evidence that signal transduction events controlled by SH2D1A are essential for B cell activities resulting in antigen specific IgG production. Defects in naive SH2D1A(-/-) B cells became evident upon cotransfer with non-primed wt CD4(+) cells into Rag2(-/-) recipients. Thus, both defective T and B cells exist in the absence of SH2D1A, which may explain the progressive dysgammaglobulinemia in a subset of X-linked lympho-proliferative disease patients without involvement of Epstein-Barr virus.

Aasa-Chapman MM, Holuigue S, Aubin K, Wong M, Jones NA, Cornforth D, Pellegrino P, Newton P, Williams I, Borrow P, McKnight A. 2005. Detection of antibody-dependent complement-mediated inactivation of both autologous and heterologous virus in primary human immunodeficiency virus type 1 infection. J Virol, 79 (5), pp. 2823-2830. | Show Abstract | Read more

Specific CD8 T-cell responses to human immunodeficiency virus type 1 (HIV-1) are induced in primary infection and make an important contribution to the control of early viral replication. The importance of neutralizing antibodies in containing primary viremia is questioned because they usually arise much later. Nevertheless antienvelope antibodies develop simultaneously with, or even before, peak viremia. We determined whether such antibodies might control viremia by complement-mediated inactivation (CMI). In each of seven patients studied, antibodies capable of CMI appeared at or shortly after the peak in viremia, concomitantly with detection of virus-specific T-cell responses. The CMI was effective on both autologous and heterologous HIV-1 isolates. Activation of the classical pathway and direct viral lysis were at least partly responsible. Since immunoglobulin G (IgG)-antibodies triggered the CMI, specific memory B cells could also be induced by vaccination. Thus, consideration should be given to vaccination strategies that induce IgG antibodies capable of CMI.

Doytchinova IA, Walshe V, Borrow P, Flower DR. 2005. Towards the chemometric dissection of peptide--HLA-A*0201 binding affinity: comparison of local and global QSAR models. J Comput Aided Mol Des, 19 (3), pp. 203-212. | Show Abstract | Read more

The affinities of 177 nonameric peptides binding to the HLA-A*0201 molecule were measured using a FACS-based MHC stabilisation assay and analysed using chemometrics. Their structures were described by global and local descriptors, QSAR models were derived by genetic algorithm, stepwise regression and PLS. The global molecular descriptors included molecular connectivity chi indices, kappa shape indices, E-state indices, molecular properties like molecular weight and log P, and three-dimensional descriptors like polarizability, surface area and volume. The local descriptors were of two types. The first used a binary string to indicate the presence of each amino acid type at each position of the peptide. The second was also position-dependent but used five z-scales to describe the main physicochemical properties of the amino acids forming the peptides. The models were developed using a representative training set of 131 peptides and validated using an independent test set of 46 peptides. It was found that the global descriptors could not explain the variance in the training set nor predict the affinities of the test set accurately. Both types of local descriptors gave QSAR models with better explained variance and predictive ability. The results suggest that, in their interactions with the MHC molecule, the peptide acts as a complicated ensemble of multiple amino acids mutually potentiating each other.

Cited:

61

WOS

Aasa-Chapman MMI, Holuigue S, Aubin K, Wong M, Jones NA, Cornforth D, Pellegrino P, Newton P, Williams I, Borrow P, Mcknight A. 2005. Detection of antibody-dependent complement-mediated inactivation of both autologous and heterologous virus in primary human immunodeficiency virus type I infection JOURNAL OF VIROLOGY, 79 (5), pp. 2823-2830. | Read more

Montoya M, Edwards MJ, Reid DM, Borrow P. 2005. Rapid activation of spleen dendritic cell subsets following lymphocytic choriomeningitis virus infection of mice: analysis of the involvement of type 1 IFN. J Immunol, 174 (4), pp. 1851-1861. | Show Abstract

In this study, we report the dynamic changes in activation and functions that occur in spleen dendritic cell (sDC) subsets following infection of mice with a natural murine pathogen, lymphocytic choriomeningitis virus (LCMV). Within 24 h postinfection (pi), sDCs acquired the ability to stimulate naive LCMV-specific CD8+ T cells ex vivo. Conventional (CD11chigh CD8+ and CD4+) sDC subsets rapidly up-regulated expression of costimulatory molecules and began to produce proinflammatory cytokines. Their tendency to undergo apoptosis ex vivo simultaneously increased, and in vivo the number of conventional DCs in the spleen decreased markedly, dropping approximately 2-fold by day 3 pi. Conversely, the number of plasmacytoid (CD11clowB220+) DCs in the spleen increased, so that they constituted almost 40% of sDCs by day 3 pi. Type 1 IFN production was up-regulated in plasmacytoid DCs by 24 h pi. Analysis of DC activation and maturation in mice unable to respond to type 1 IFNs implicated these cytokines in driving infection-associated phenotypic activation of conventional DCs and their enhanced tendency to undergo apoptosis, but also indicated the existence of type 1 IFN-independent pathways for the functional maturation of DCs during LCMV infection.

Borrow P, Hou S, Gloster S, Ashton M, Hyland L. 2005. Virus infection-associated bone marrow B cell depletion and impairment of humoral immunity to heterologous infection mediated by TNF-alpha/LTalpha. Eur J Immunol, 35 (2), pp. 524-532. | Show Abstract | Read more

We previously showed that influenza virus infection of mice induces a depletion of bone marrow B lineage cells due to apoptosis of early B cells mediated by a mechanism involving TNF-alpha/LTalpha. Here we demonstrate that this effect is also observed with acute lymphocytic choriomeningitis virus (LCMV) infection and resulted in a deficiency of both splenic transitional B cells and mature follicular B cells. To determine whether there was an associated impairment of humoral immunity, we infected mice with LCMV and 10 days later at the peak of the B cell depletion, inoculated them with influenza virus. We found that influenza virus-specific antibody titers were dramatically reduced in mice recovering from LCMV infection compared to those in mice infected with influenza virus alone. Further, we showed that there was no reduction of the influenza virus-specific antibody response in LCMV-infected TNF-alpha/LTalpha-deficient mice, suggesting that TNF-alpha/LTalpha-mediated effects on bone marrow and/or peripheral lymphocytes were responsible for the observed impairment in humoral immunity. These results show that the TNF-alpha/LTalpha production induced following infection with diverse viruses has detrimental effects on early B cells in the bone marrow, and may be among the factors that lead to the severely compromised humoral immunity observed to subsequent heterologous infections.

Jones NA, Wei X, Flower DR, Wong M, Michor F, Saag MS, Hahn BH, Nowak MA, Shaw GM, Borrow P. 2004. Determinants of human immunodeficiency virus type 1 escape from the primary CD8+ cytotoxic T lymphocyte response. J Exp Med, 200 (10), pp. 1243-1256. | Show Abstract | Read more

CD8+ cytotoxic T lymphocytes (CTLs) play an important role in containment of virus replication in primary human immunodeficiency virus (HIV) infection. HIV's ability to mutate to escape from CTL pressure is increasingly recognized; but comprehensive studies of escape from the CD8 T cell response in primary HIV infection are currently lacking. Here, we have fully characterized the primary CTL response to autologous virus Env, Gag, and Tat proteins in three patients, and investigated the extent, kinetics, and mechanisms of viral escape from epitope-specific components of the response. In all three individuals, we observed variation beginning within weeks of infection at epitope-containing sites in the viral quasispecies, which conferred escape by mechanisms including altered peptide presentation/recognition and altered antigen processing. The number of epitope-containing regions exhibiting evidence of early CTL escape ranged from 1 out of 21 in a subject who controlled viral replication effectively to 5 out of 7 in a subject who did not. Evaluation of the extent and kinetics of HIV-1 escape from >40 different epitope-specific CD8 T cell responses enabled analysis of factors determining escape and suggested that escape is restricted by costs to intrinsic viral fitness and by broad, codominant distribution of CTL-mediated pressure on viral replication.

Tchilian EZ, Dawes R, Hyland L, Montoya M, Le Bon A, Borrow P, Hou S, Tough D, Beverley PC. 2004. Altered CD45 isoform expression affects lymphocyte function in CD45 Tg mice. Int Immunol, 16 (9), pp. 1323-1332. | Show Abstract | Read more

Transgenic mice have been constructed expressing high (CD45RABC) and low (CD45R0) molecular weight CD45 isoforms on a CD45-/- background. Phenotypic analysis and in vivo challenge of these mice with influenza and lymphocytic choriomeningitis viruses shows that T cell differentiation and peripheral T cell function are related to the level of CD45 expression but not to which CD45 isoform is expressed. In contrast, B cell differentiation is not restored, irrespective of the level of expression of a single isoform. All CD45 trangenic mice have T cells with an activated phenotype and increased T cell turnover. These effects are more prominent in CD8 than CD4 cells. The transgenic mice share several properties with humans expressing variant CD45 alleles and provide a model to understand immune function in variant individuals.

Doytchinova IA, Walshe VA, Jones NA, Gloster SE, Borrow P, Flower DR. 2004. Coupling in silico and in vitro analysis of peptide-MHC binding: a bioinformatic approach enabling prediction of superbinding peptides and anchorless epitopes. J Immunol, 172 (12), pp. 7495-7502. | Show Abstract

The ability to define and manipulate the interaction of peptides with MHC molecules has immense immunological utility, with applications in epitope identification, vaccine design, and immunomodulation. However, the methods currently available for prediction of peptide-MHC binding are far from ideal. We recently described the application of a bioinformatic prediction method based on quantitative structure-affinity relationship methods to peptide-MHC binding. In this study we demonstrate the predictivity and utility of this approach. We determined the binding affinities of a set of 90 nonamer peptides for the MHC class I allele HLA-A*0201 using an in-house, FACS-based, MHC stabilization assay, and from these data we derived an additive quantitative structure-affinity relationship model for peptide interaction with the HLA-A*0201 molecule. Using this model we then designed a series of high affinity HLA-A2-binding peptides. Experimental analysis revealed that all these peptides showed high binding affinities to the HLA-A*0201 molecule, significantly higher than the highest previously recorded. In addition, by the use of systematic substitution at principal anchor positions 2 and 9, we showed that high binding peptides are tolerant to a wide range of nonpreferred amino acids. Our results support a model in which the affinity of peptide binding to MHC is determined by the interactions of amino acids at multiple positions with the MHC molecule and may be enhanced by enthalpic cooperativity between these component interactions.

Gloster SE, Newton P, Cornforth D, Lifson JD, Williams I, Shaw GM, Borrow P. 2004. Association of strong virus-specific CD4 T cell responses with efficient natural control of primary HIV-1 infection. AIDS, 18 (5), pp. 749-755. | Show Abstract | Read more

OBJECTIVE: To investigate whether there are differences in the virus-specific CD4 T cell response during primary HIV-1 infection in patients who naturally (without antiretroviral intervention) control viral replication with differing efficiencies. METHODS: CD4 T cell responses to recombinant HIV proteins (Gag p24 and p55 and Env gp160) and an inactivated HIV-1 preparation were analysed using interferon-gamma ELISPOT assays (with CD8-depleted peripheral blood mononuclear cells) and by intracellular interferon-gamma staining and fluorescent-activated cell sorting. RESULTS: Strong HIV-specific CD4 T cell responses were detected from the earliest time-points analysed in primary infection in patients who naturally established low persisting viral loads. By contrast, HIV-specific CD4 T cell responses were weaker (at or just below the limit of detection in our assays) at similar time-points in patients who went on to establish high persisting viral loads. Statistical analysis revealed a highly significant difference (P < 0.001) between the magnitudes of the Gag p24-specific response at the earliest time-point analysed in primary infection in the two sets of patients. CONCLUSIONS: Strong HIV-specific CD4 T cell responses are associated with efficient natural control of primary HIV-1 infection.

Aasa-Chapman MM, Hayman A, Newton P, Cornforth D, Williams I, Borrow P, Balfe P, McKnight A. 2004. Development of the antibody response in acute HIV-1 infection. AIDS, 18 (3), pp. 371-381. | Show Abstract | Read more

BACKGROUND: Cytotoxic T lymphocytes have been shown to reduce viraemia during acute HIV-1 infection; however the role of neutralizing antibodies in this process is unclear. One confounding factor may be artefacts introduced by viral culture. OBJECTIVE: To assess the development of autologous neutralizing and non-neutralizing antibodies following acute HIV-1 infection using recombinant viruses with envelopes amplified directly from patient peripheral blood mononuclear cells, thereby avoiding in vitro selection. METHODS: Disease progression in four homosexual men was monitored from acute infection for up to 2.5 years, in the absence of antiretroviral therapy. Antibodies to viral envelope protein were quantified by enzyme-linked immunosorbent assay. Development of neutralizing antibodies was monitored using a quantitative infectivity reduction assay, sequential serum, recombinant viruses and target cells with defined receptor expression. RESULTS: The time to development of neutralizing antibodies after onset of symptoms was 3, 5, 7 and 16 months in the four patients. There was no correlation between development of neutralizing antibodies and the resolution of viraemia in any of the patients. However, antibodies to the envelope were detectable as early as 2 weeks after onset of symptoms. CONCLUSIONS: Neutralizing antibodies do not contribute to the control of viraemia in acute HIV-1 infection. However, antibodies to the envelope could be detected at the time of reduction in plasma viraemia and so other effector functions of antibodies may play a role in viral clearance.

Le Bon A, Etchart N, Rossmann C, Ashton M, Hou S, Gewert D, Borrow P, Tough DF. 2003. Cross-priming of CD8+ T cells stimulated by virus-induced type I interferon. Nat Immunol, 4 (10), pp. 1009-1015. | Show Abstract | Read more

CD8+ T cell responses can be generated against antigens that are not expressed directly within antigen-presenting cells (APCs), through a process known as cross-priming. To initiate cross-priming, APCs must both capture extracellular antigen and receive specific activation signals. We have investigated the nature of APC activation signals associated with virus infection that stimulate cross-priming. We show that infection with lymphocytic choriomeningitis virus induces cross-priming by a mechanism dependent on type I interferon (IFN-alpha/beta). Activation of cross-priming by IFN-alpha/beta was independent of CD4+ T cell help or interaction of CD40 and CD40 ligand, and involved direct stimulation of dendritic cells. These data identify expression of IFN-alpha/beta as a mechanism for the induction of cross-priming during virus infections.

Diebold SS, Montoya M, Unger H, Alexopoulou L, Roy P, Haswell LE, Al-Shamkhani A, Flavell R, Borrow P, Reis e Sousa C. 2003. Viral infection switches non-plasmacytoid dendritic cells into high interferon producers. Nature, 424 (6946), pp. 324-328. | Show Abstract | Read more

Type I interferons (IFN-I) are important cytokines linking innate and adaptive immunity. Plasmacytoid dendritic cells make high levels of IFN-I in response to viral infection and are thought to be the major source of the cytokines in vivo. Here, we show that conventional non-plasmacytoid dendritic cells taken from mice infected with a dendritic-cell-tropic strain of lymphocytic choriomeningitis virus make similarly high levels of IFN-I on subsequent culture. Similarly, non-plasmacytoid dendritic cells secrete high levels of IFN-I in response to double-stranded RNA (dsRNA), a major viral signature, when the latter is introduced into the cytoplasm to mimic direct viral infection. This response is partially dependent on the cytosolic dsRNA-binding enzyme protein kinase R and does not require signalling through toll-like receptor (TLR) 3, a surface receptor for dsRNA. Furthermore, we show that sequestration of dsRNA by viral NS1 (refs 6, 7) explains the inability of conventional dendritic cells to produce IFN-I on infection with influenza. Our results suggest that multiple dendritic cell types, not just plasmacytoid cells, can act as specialized interferon-producing cells in certain viral infections, and reveal the existence of a TLR-independent pathway for dendritic cell activation that can be the target of viral interference.

Lopes AR, Jaye A, Dorrell L, Sabally S, Alabi A, Jones NA, Flower DR, De Groot A, Newton P, Lascar RM et al. 2003. Greater CD8+ TCR heterogeneity and functional flexibility in HIV-2 compared to HIV-1 infection. J Immunol, 171 (1), pp. 307-316. | Show Abstract

Virus-specific CD8(+) T cells are known to play an important role in the control of HIV infection. In this study we investigated whether there may be qualitative differences in the CD8(+) T cell response in HIV-1- and HIV-2-infected individuals that contribute to the relatively efficient control of the latter infection. A molecular comparison of global TCR heterogeneity showed a more oligoclonal pattern of CD8 cells in HIV-1- than HIV-2-infected patients. This was reflected in restricted and conserved TCR usage by CD8(+) T cells recognizing individual HLA-A2- and HLA-B57-restricted viral epitopes in HIV-1, with limited plasticity in their response to amino acid substitutions within these epitopes. The more diverse TCR usage observed for HIV-2-specific CD8(+) T cells was associated with an enhanced potential for CD8 expansion and IFN-gamma production on cross-recognition of variant epitopes. Our data suggest a mechanism that could account for any possible cross-protection that may be mediated by HIV-2-specific CD8(+) T cells against HIV-1 infection. Furthermore, they have implications for HIV vaccine development, demonstrating an association between a polyclonal, virus-specific CD8(+) T cell response and an enhanced capacity to tolerate substitutions within T cell epitopes.

Wakatsuki A, Borrow P, Rigley K, Beverley PC. 2003. Cell-surface bound pertussis toxin induces polyclonal T cell responses with high levels of interferon-gamma in the absence of interleukin-12. Eur J Immunol, 33 (7), pp. 1859-1868. | Show Abstract | Read more

Pertussis toxin (PTx), an exotoxin produced by Bordetella pertussis, has long been used as a mucosal adjuvant. We examined the T cell stimulatory properties of PTx in order to dissect its mechanisms of adjuvanticity. PTx or the B-oligomer of PTx (PTxB) failed to activate purified murine CD4+ or CD8+ T cells, as measured by a lack of proliferation or expression of early T cell activation markers. However, these T cells proliferated extensively in response to the toxin in the presence of syngeneic DC, and proliferation was accompanied by a high level of IFN-gamma production in the absence of IL-12. Interestingly, such responses were independent of signals mediated by MHC-TCR interaction. Both PTx and PTxB were found to bind stably to the surface of DC, and increased the adherence of DC to surrounding cells. These data suggest that polyclonal T cell responses mediated by the toxin are likely to be caused by the toxin bound on the surface of APC, either cross-linking cell surface molecules on T cells, or directly stimulating T cells together with the co-stimulatory molecules expressed on APC. B. pertussis may use this toxin as a mechanism to evade a specific immune response.

Lucas M, Tsitoura E, Montoya M, Laliotou B, Aslanoglou E, Kouvatsis V, Entwisle C, Miller J, Klenerman P, Hadziyannis A et al. 2003. Characterization of secreted and intracellular forms of a truncated hepatitis C virus E2 protein expressed by a recombinant herpes simplex virus. J Gen Virol, 84 (Pt 3), pp. 545-554. | Show Abstract | Read more

A replication-defective herpes simplex virus type 1 (HSV-1) recombinant lacking the glycoprotein H (gH)-encoding gene and expressing a truncated form of the hepatitis C (HCV) E2 glycoprotein (E2-661) was constructed and characterized. We show here that cells infected with the HSV/HCV recombinant virus efficiently express the HCV E2-661 protein. Most importantly, cellular and secreted E2-661 protein were both readily detected by the E2-conformational mAb H53 and despite the high expression levels, only limited amounts of misfolded aggregates were detected in either the cellular or secreted fractions. Furthermore, cell-associated and secreted E2-661 protein bound to the major extracellular loop (MEL) of CD81 in a concentration-dependent manner and both were highly reactive with sera from HCV-infected patients. Finally, BALB/c mice immunized intraperitoneally with the recombinant HSV/HCV virus induced high levels of anti-E2 antibodies. Analysis of the induced immunoglobulin G (IgG) isotypes showed high levels of IgG2a while the levels of the IgG1 isotype were significantly lower, suggesting a Th1-type of response. We conclude that the HSV-1 recombinant virus represents a promising tool for production of non-aggregated, immunologically active forms of the E2-661 protein and might have potential applications in vaccine development.

Flower DR, McSparron H, Blythe MJ, Zygouri C, Taylor D, Guan P, Wan S, Coveney PV, Walshe V, Borrow P, Doytchinova IA. 2003. Computational vaccinology: quantitative approaches. Novartis Found Symp, 254 pp. 102-120. | Show Abstract

The immune system is hierarchical and has many levels, exhibiting much emergent behaviour. However, at its heart are molecular recognition events that are indistinguishable from other types of biomacromolecular interaction. These can be addressed well by quantitative experimental and theoretical biophysical techniques, and particularly by methods from drug design. We review here our approach to computational immunovaccinology. In particular, we describe the JenPep database and two new techniques for T cell epitope prediction. One is based on quantitative structure-activity relationships (a 3D-QSAR method based on CoMSIA and another 2D method based on the Free-Wilson approach) and the other on atomistic molecular dynamic simulations using high performance computing. JenPep (http://www.jenner.ar.uk/ JenPep) is a relational database system supporting quantitative data on peptide binding to major histocompatibility complexes, TAP transporters, TCR-pMHC complexes, and an annotated list of B cell and T cell epitopes. Our 2D-QSAR method factors the contribution to peptide binding from individual amino acids as well as 1-2 and 1-3 residue interactions. In the 3D-QSAR approach, the influence of five physicochemical properties (volume, electrostatic potential, hydrophobicity, hydrogen-bond donor and acceptor abilities) on peptide affinity were considered. Both methods are exemplified through their application to the well-studied problem of peptide binding to the human class I MHC molecule HLA-A*0201.

Montoya M, Schiavoni G, Mattei F, Gresser I, Belardelli F, Borrow P, Tough DF. 2002. Type I interferons produced by dendritic cells promote their phenotypic and functional activation. Blood, 99 (9), pp. 3263-3271. | Show Abstract | Read more

Resting dendritic cells (DCs) are resident in most tissues and can be activated by environmental stimuli to mature into potent antigen-presenting cells. One important stimulus for DC activation is infection; DCs can be triggered through receptors that recognize microbial components directly or by contact with infection-induced cytokines. We show here that murine DCs undergo phenotypic maturation upon exposure to type I interferons (type I IFNs) in vivo or in vitro. Moreover, DCs either derived from bone marrow cells in vitro or isolated from the spleens of normal animals express IFN-alpha and IFN-beta, suggesting that type I IFNs can act in an autocrine manner to activate DCs. Consistent with this idea, the ability to respond to type I IFN was required for the generation of fully activated DCs from bone marrow precursors, as DCs derived from the bone marrow of mice lacking a functional receptor for type I IFN had reduced expression of costimulatory and adhesion molecules and a diminished ability to stimulate naive T-cell proliferation compared with DCs derived from control bone marrow. Furthermore, the addition of neutralizing anti-IFN-alpha/beta antibody to purified splenic DCs in vitro partially blocked the "spontaneous" activation of these cells, inhibiting the up-regulation of costimulatory molecules, secretion of IFN-gamma, and T-cell stimulatory activity. These results show that DCs both secrete and respond to type I IFN, identifying type I interferons as autocrine DC activators.

Kunz S, Borrow P, Oldstone MB. 2002. Receptor structure, binding, and cell entry of arenaviruses. Curr Top Microbiol Immunol, 262 pp. 111-137.

Vázquez Blomquist D, Green P, Laidlaw SM, Skinner MA, Borrow P, Duarte CA. 2002. Induction of a strong HIV-specific CD8+ T cell response in mice using a fowlpox virus vector expressing an HIV-1 multi-CTL-epitope polypeptide. Viral Immunol, 15 (2), pp. 337-356. | Show Abstract | Read more

Recombinant avipoxvirus vectors are attractive candidates for use in vaccination strategies for infections such as human immunodeficiency virus type 1 (HIV-1), where induction of a CD8+ T cell response is thought to be an important component of protective immunity. Here, we report the expression of a multiepitope polypeptide (TAB9) composed of the central 15 amino acids of the V3 loop from six different isolates of HIV-1 in a fowlpox virus (FWPV) vector, and the use of this vector (FPTAB9LZ) to induce strong HIV-specific CD8+ T cell responses in mice. In animals immunized twice intravenously with FPTAB9LZ, almost 2% of the CD8+ T cells in the spleen were shown to produce IFN-gamma in response to stimulation with HIV-1 peptides 1 week after the second immunization. The most dominant response was to the HIV-1 IIIB peptide. A strong HIV-specific response was also induced by intraperitoneal immunization of mice with FPTAB9LZ, whilst subcutaneous immunization elicited a weaker response. Intraperitoneal immunization with FPTAB9LZ was also shown to provide protection against challenge with a recombinant vaccinia virus expressing antigens, including those in TAB9. These results confirm the potential of FWPV vectors for use in HIV vaccination strategies.

Rescigno M, Borrow P. 2001. The host-pathogen interaction: new themes from dendritic cell biology. Cell, 106 (3), pp. 267-270. | Read more

Wu C, Nguyen KB, Pien GC, Wang N, Gullo C, Howie D, Sosa MR, Edwards MJ, Borrow P, Satoskar AR et al. 2001. SAP controls T cell responses to virus and terminal differentiation of TH2 cells. Nat Immunol, 2 (5), pp. 410-414. | Show Abstract | Read more

SH2D1A, which encodes signaling lymphocyte activation molecule (SLAM)-associated protein (SAP), is altered in patients with X-linked lymphoproliferative disease (XLP), a primary immunodeficiency. SAP-deficient mice infected with lymphocytic choriomeningitis virus had greatly increased numbers of CD8+ and CD4+ interferon-gamma-producing spleen and liver cells compared to wild-type mice. The immune responses of SAP-deficient mice to infection with Leishmania major together with in vitro studies showed that activated SAP-deficient T cells had an impaired ability to differentiate into T helper 2 cells. The aberrant immune responses in SAP-deficient mice show that SAP controls several distinct key T cell signal transduction pathways, which explains in part the complexity of the XLP phenotypes.

Smelt SC, Borrow P, Kunz S, Cao W, Tishon A, Lewicki H, Campbell KP, Oldstone MB. 2001. Differences in affinity of binding of lymphocytic choriomeningitis virus strains to the cellular receptor alpha-dystroglycan correlate with viral tropism and disease kinetics. J Virol, 75 (1), pp. 448-457. | Show Abstract | Read more

alpha-Dystroglycan (alpha-DG) was recently identified as a receptor for lymphocytic choriomeningitis virus (LCMV) and several other arenaviruses, including Lassa fever virus (W. Cao, M. D. Henry, P. Borrow, H. Yamada, J. H. Elder, E. V. Ravkov, S. T. Nichol, R. W. Compans, K. P. Campbell, and M. B. A. Oldstone, Science 282:2079-2081, 1998). Data presented in this paper indicate that the affinity of binding of LCMV to alpha-DG determines viral tropism and the outcome of infection in mice. To characterize this relationship, we evaluated the interaction between alpha-DG and several LCMV strains, variants, and reassortants. These viruses could be divided into two groups with respect to affinity of binding to alpha-DG, dependence on this protein for cell entry, viral tropism, and disease course. Viruses that exhibited high-affinity binding to alpha-DG displayed a marked dependence on alpha-DG for cell entry and were blocked from infecting mouse 3T6 fibroblasts by 1 to 4 nM soluble alpha-DG. In addition, high-affinity binding to alpha-DG correlated with an ability to infiltrate the white pulp (T-dependent) area of the spleen, cause ablation of the cytotoxic T-lymphocyte (CTL) response by day 7 postinfection, and establish a persistent infection. In contrast, viruses with a lower affinity of binding to alpha-DG were only partially inhibited from infecting alpha-DG(-/-) embryonic stem cells and required a concentration of soluble alpha-DG higher than 100 nM to prevent infection of mouse 3T6 fibroblasts. These viruses that bound at low affinity were mainly restricted to the splenic red pulp, and the host generated an effective CTL response that rapidly cleared the infection. Reassortants of viruses that bound to alpha-DG at high and low affinities were used to map genes responsible for the differences described to the S RNA, containing the virus attachment protein glycoprotein 1.

Flint M, Dubuisson J, Maidens C, Harrop R, Guile GR, Borrow P, McKeating JA. 2000. Functional characterization of intracellular and secreted forms of a truncated hepatitis C virus E2 glycoprotein. J Virol, 74 (2), pp. 702-709. | Show Abstract | Read more

The E2 protein of hepatitis C virus (HCV) is believed to be a virion surface glycoprotein that is a candidate for inclusion in an antiviral vaccine. A truncated soluble version of E2 has recently been shown to interact with CD81, suggesting that this protein may be a component of the receptor for HCV. When expressed in eukaryotic cells, a significant proportion of E2 forms misfolded aggregates. To analyze the specificity of interaction between E2 and CD81, the aggregated and monomeric forms of a truncated E2 glycoprotein (E2(661)) were separated by high-pressure liquid chromatography and analyzed for CD81 binding. Nonaggregated forms of E2 preferentially bound CD81 and a number of conformation-dependent monoclonal antibodies (MAbs). Furthermore, intracellular forms of E2(661) were found to bind CD81 with greater affinity than the extracellular forms. Intracellular and secreted forms of E2(661) were also found to differ in reactivity with MAbs and human sera, consistent with differences in antigenicity. Together, these data indicate that proper folding of E2 is important for its interaction with CD81 and that modifications of glycans can modulate this interaction. Identification of the biologically active forms of E2 will assist in the future design of vaccines to protect against HCV infection.

Guidotti LG, Borrow P, Brown A, McClary H, Koch R, Chisari FV. 1999. Noncytopathic clearance of lymphocytic choriomeningitis virus from the hepatocyte. J Exp Med, 189 (10), pp. 1555-1564. | Show Abstract | Read more

We have previously shown that interferon and tumor necrosis factor noncytopathically abolish hepatitis B virus (HBV) replication from the hepatocyte and kidney tubular epithelial cells in vivo. Here we show that a persistent lymphocytic choriomeningitis virus (LCMV) infection is cleared from the hepatocyte noncytopathically when the same cytokines are induced in the liver by antigen-nonspecific stimuli. These results indicate that, like HBV, LCMV is also susceptible to intracellular inactivation by cytokine-induced antiviral mechanisms that are operative in the hepatocyte. In contrast, LCMV is not cleared from intrahepatic nonparenchymal cells or splenocytes, indicating that, unlike the hepatocyte, these cells do not produce the factors required to inactivate LCMV. Antiviral mechanisms like these may have evolved to maintain the functional integrity of vital organs in the face of massive infection.

Cao W, Henry MD, Borrow P, Yamada H, Elder JH, Ravkov EV, Nichol ST, Compans RW, Campbell KP, Oldstone MB. 1998. Identification of alpha-dystroglycan as a receptor for lymphocytic choriomeningitis virus and Lassa fever virus. Science, 282 (5396), pp. 2079-2081. | Show Abstract | Read more

A peripheral membrane protein that is interactive with lymphocytic choriomeningitis virus (LCMV) was purified from cells permissive to infection. Tryptic peptides from this protein were determined to be alpha-dystroglycan (alpha-DG). Several strains of LCMV and other arenaviruses, including Lassa fever virus (LFV), Oliveros, and Mobala, bound to purified alpha-DG protein. Soluble alpha-DG blocked both LCMV and LFV infection. Cells bearing a null mutation of the gene encoding DG were resistant to LCMV infection, and reconstitution of DG expression in null mutant cells restored susceptibility to LCMV infection. Thus, alpha-DG is a cellular receptor for both LCMV and LFV.

Borrow P, Tough DF, Eto D, Tishon A, Grewal IS, Sprent J, Flavell RA, Oldstone MB. 1998. CD40 ligand-mediated interactions are involved in the generation of memory CD8(+) cytotoxic T lymphocytes (CTL) but are not required for the maintenance of CTL memory following virus infection. J Virol, 72 (9), pp. 7440-7449. | Show Abstract

CD8(+) cytotoxic T lymphocytes (CTL) play a key role in the control of many virus infections, and the need for vaccines to elicit strong CD8(+) T-cell responses in order to provide optimal protection in such infections is increasingly apparent. However, the mechanisms involved in the induction and maintenance of CD8(+) CTL memory are currently poorly understood. In this study, we investigated the involvement of CD40 ligand (CD40L)-mediated interactions in these processes by analyzing the memory CTL response of CD40L-deficient mice following infection with lymphocytic choriomeningitis virus (LCMV). The maintenance of memory CD8(+) CTL precursors (CTLp) at stable frequencies over time was not impaired in CD40L-deficient mice. By contrast, the initial generation of memory CTLp was affected. CD40L-deficient mice produced lower levels of CD8(+) CTLp during the primary immune response to LCMV than did wild-type controls, despite the fact that the LCMV-specific effector CTL response of CD40L-deficient mice was indistinguishable from that of control animals. The differentiation of naïve CD8(+) T cells into effector and memory CTL thus involves pathways that can be discriminated from each other by their requirement for CD40L-mediated interactions. Expression of CD40L by CTLp themselves was not an essential step during their expansion and differentiation from naïve CD8(+) cells into memory CTLp; instead, the reduction in memory CTLp generation in CD40L-deficient mice was likely a consequence of defects in the CD4(+) T-cell response mounted by these animals. These results thus suggest a previously unappreciated role for CD40L in the generation of CD8(+) memory CTLp, the probable nature of which is discussed.

Borrow P, Shaw GM. 1998. Cytotoxic T-lymphocyte escape viral variants: how important are they in viral evasion of immune clearance in vivo? Immunol Rev, 164 (1), pp. 37-51. | Show Abstract | Read more

Although viral variants which are not recognized by epitope-specific cytotoxic T lymphocytes (CTL) have been shown to arise during a number of persistent virus infections, in many cases their significance remains controversial: it has been argued that the immune response is sufficiently plastic to contain their replication. In this review, we describe the mechanisms by which amino acid changes in viral proteins may affect epitope recognition by virus-specific CTL, and discuss the viral and immunological basis for the emergence of viral variants bearing such amino acid changes during infection. We then consider the impact that viral variation may have on the host CTL response and its ability to contain virus replication. We argue that the emergence of a viral variant demonstrates that it must have an in vivo replicative advantage, and that as such, the variant must tip the balance between virus replication and immune control somewhat in favor of the virus. Further, we suggest that although the immune response can evolve to recognize new viral epitopes, the CTL generated following such evolution frequently have a reduced ability to contain virus replication. We conclude that this escape mechanism likely does make a significant contribution to persistence/pathogenesis during a number of different virus infections.

Borrow P, Welsh CJ, Tonks P, Dean D, Blakemore WF, Nash AA. 1998. Investigation of the role of delayed-type-hypersensitivity responses to myelin in the pathogenesis of Theiler's virus-induced demyelinating disease. Immunology, 93 (4), pp. 478-484. | Show Abstract | Read more

The contribution of autoimmune responses to the pathogenesis of Theiler's virus-induced demyelinating disease was investigated. Delayed-type hypersensitivity responses to myelin were examined in both symptomatic and asymptomatic mice at different times post-infection, in order to determine whether autoreactivity correlates with the development of demyelination. The results indicate that although autoimmune responses probably do not play a major role in the initiation of demyelination at early times post-infection, autoreactivity to myelin antigens dose eventually develop in symptomatic animals, perhaps through the mechanism of epitope spreading. Autoimmunity to myelin components is therefore an additional factor that may contribute to lesion progression in chronically diseased animals.

Luxembourg AT, Borrow P, Teyton L, Brunmark AB, Peterson PA, Jackson MR. 1998. Biomagnetic isolation of antigen-specific CD8+ T cells usable in immunotherapy. Nat Biotechnol, 16 (3), pp. 281-285. | Show Abstract | Read more

Isolating antigen-specific T lymphocytes is hampered by the low frequency of the cells and the low affinity between T-cell receptors (TCR) and antigen. We describe the isolation and purification of antigen-specific CD8+ T lymphocytes from mixed T-cell populations. Magnetic beads coated with major histocompatibility complex class I molecules loaded with specific peptide were used as a substrate for T-cell capture. Low-frequency T cells, as well as T cells with TCR of low affinity for the antigen were captured on the beads. Following isolation and expansion, recovered cells specifically killed target cells in vitro, and displayed antiviral effect in vivo.

de la Torre JC, Borrow P. 1998. Chapter 22 Virus-induced alterations in cells Principles of Medical Biology, 9 (C), pp. 365-379. | Show Abstract | Read more

Virus-induced disease occurs as a result of both direct cell destruction caused by virus replication and damage to the infected cells due to the host immune response obtained against the infectious agent. In addition, viruses are also able to escape from the host's immunological surveillance and adapt a strategy of nonlytic replication, thus establishing persistent, or chronic infections during which the typical hallmarks of virus infection-cytolysis and inflammation-are not present, but the host's differentiated functions may be affected. This, in turn, can disrupt homeostasis and lead to disease. Viruses are thus likely to be responsible for a wide variety of clinical illnesses, currently of unknown etiology, that affect the endocrine, immune, nervous and other specialized cellular functions of the host. © 1997 Elsevier B.V. All rights reserved.

de Parseval A, Lerner DL, Borrow P, Willett BJ, Elder JH. 1997. Blocking of feline immunodeficiency virus infection by a monoclonal antibody to CD9 is via inhibition of virus release rather than interference with receptor binding. J Virol, 71 (8), pp. 5742-5749. | Show Abstract

A monoclonal antibody, MAb vpg15, inhibits feline immunodeficiency virus (FIV) infection in tissue culture. The antibody is directed to a determinant of the feline cell surface marker, CD9, implying that CD9 may serve as a viral receptor or coreceptor in this system. In cells expressing CD9, MAb vpg15 markedly delayed acute virus infection in terms of reverse transcriptase activity detected in cell culture supernatants. This effect was evident if the antibody was added before, immediately after, or 24 h after virus infection. Binding experiments showed that MAb vpg15 did not block virus binding to the cells. PCR analyses at various intervals postinfection also indicated that MAb vpg15 did not block virus uptake, reverse transcription of viral RNA, or integration into host cell DNA. Multiply spliced mRNAs were detected up to 24 h postinfection in both control and MAb vpg15-treated cells. However, viral mRNAs were markedly diminished in MAb vpg15-treated cells after this time, consistent with a failure of the FIV infection to spread in the cell culture. Treatment of chronically infected cells with MAb vpg15 also caused a sharp diminution in viral particle production, while viral mRNA levels were the same in both untreated and MAb-treated infected cells. Analyses of intracellular and extracellular levels of virus-associated antigens showed an enhanced accumulation of intracellular p24. These findings are consistent with the interpretation that MAb vpg15 acts at a posttranscriptional stage by interfering with the assembly and/or release of virus from the cell.

Grewal IS, Borrow P, Pamer EG, Oldstone MB, Flavell RA. 1997. The CD40-CD154 system in anti-infective host defense. Curr Opin Immunol, 9 (4), pp. 491-497. | Show Abstract | Read more

Research in the past few years has documented significant advances in our understanding of the CD40-CD40 ligand (CD154) system in diverse immune functions. This system influences many T cell mediated inflammatory immune responses and effector functions, unmasking a previously unexpected role for CD40-CD154 in cell mediated immunity. Manipulation of CD154 in animal models of infection by the use of CD154-deficient mice or anti-CD154 antibodies has shown the importance of this system in the initiation of the inflammatory response, in the activation of antigen-presenting cells and in resistance to infections.

Wyss-Coray T, Borrow P, Brooker MJ, Mucke L. 1997. Astroglial overproduction of TGF-beta 1 enhances inflammatory central nervous system disease in transgenic mice . J Neuroimmunol, 77 (1), pp. 45-50. | Show Abstract | Read more

Cerebral expression of the injury response cytokine transforming growth factor-beta 1 (TGF-beta 1) has been found to be increased in several neurological diseases but it remains unclear whether its function is primarily beneficial or detrimental. Here we show that transgenic (tg) mice that overexpress bioactive (TGF-beta 1 in the central nervous system (CNS) and show no overt phenotype in the unmanipulated state, are more susceptible to the immune-mediated CNS disease experimental autoimmune encephalomyelitis (EAE). TGF-beta 1 tg mice with EAE showed an earlier onset of clinical symptoms, more severe disease and increased mononuclear cell infiltration in their spinal cords compared with non-tg littermate controls with EAE. Whereas previous observations indicated that increased peripheral levels of TGF-beta 1 can suppress EAE, our findings demonstrate that local expression of TGF-beta 1 within the CNS parenchyma can enhance immune cell infiltration and intensify the CNS impairment resulting from peripherally triggered autoimmune responses.

Borrow P, Lewicki H, Wei X, Horwitz MS, Peffer N, Meyers H, Nelson JA, Gairin JE, Hahn BH, Oldstone MB, Shaw GM. 1997. Antiviral pressure exerted by HIV-1-specific cytotoxic T lymphocytes (CTLs) during primary infection demonstrated by rapid selection of CTL escape virus. Nat Med, 3 (2), pp. 205-211. | Show Abstract | Read more

The HIV-1-specific cytotoxic T lymphocyte (CTL) response is temporally associated with the decline in viremia during primary HIV-1 infection, but definitive evidence that it is of importance in virus containment has been lacking. Here we show that in a patient whose early CTL response was focused on a highly immunodominant epitope in gp 160, there was rapid elimination of the transmitted virus strain and selection for a virus population bearing amino acid changes at a single residue within this epitope, which conferred escape from recognition by epitope-specific CTL. The magnitude (> 100-fold), kinetics (30-72 days from onset of symptoms) and genetic pathways of virus escape from CTL pressure were comparable to virus escape from antiretroviral therapy, indicating the biological significance of the CTL response in vivo. One aim of HIV-1 vaccines should thus be to elicit strong CTL responses against multiple codominant viral epitopes.

Borrow P. 1997. Mechanisms of viral clearance and persistence. J Viral Hepat, 4 Suppl 2 (s2), pp. 16-24. | Show Abstract | Read more

Using examples predominantly drawn from study of the lymphocytic choriomeningitis virus (LCMV) model system, this review describes the mechanisms involved in control of virus infections by the cell-mediated immune response, and some of the different strategies viruses have evolved to evade such immune clearance so that they can persist in their hosts. The important role played by the CD8+ cytotoxic lymphocyte (CTL) response in clearance of many systemic virus infections is discussed; and it is emphasized that although CD8+ CTL are classically thought of as lymphocytes which mediate lysis of virus-infected target cells, the principal mechanism by which CD8+ T cells effect clearance of persistent and many acute virus infections via production of antiviral cytokines such as tumour necrosis factor-alpha and interferon-gamma, not via destruction of virus-producing cells. To avoid immune-mediated clearance, viruses frequently use a combination of several different strategies. These can be grouped into mechanisms for avoiding recognition by the immune response (such as establishing latent infections, replicating in immune-privileged sites, down-regulating the expression of immune recognition signals on the surface of infected cells, or undergoing antigenic variation); and mechanisms for suppressing the immune response. The latter include generalized immune suppression mechanisms, and strategies for more precisely disabling the specific immune response such as inducing tolerance or exhaustion of virus-specific CTL. The value of understanding both immune clearance mechanisms and viral evasion strategies in the rational design of immune-based therapies to combat persistent virus infections is discussed.

Teng MN, Borrow P, Oldstone MB, de la Torre JC. 1996. A single amino acid change in the glycoprotein of lymphocytic choriomeningitis virus is associated with the ability to cause growth hormone deficiency syndrome. J Virol, 70 (12), pp. 8438-8443. | Show Abstract

Persistent infection of C3H/St mice with certain strains of lymphocytic choriomeningitis virus (LCMV) causes a growth hormone (GH) deficiency syndrome (GHDS) manifested as growth retardation and hypoglycemia. Infected mice show high levels of viral replication in the GH-producing cells in the anterior pituitary leading to decreased synthesis of GH mRNA and protein despite the absence of detectable virus-induced cell structural damage. Virus clones isolated from the GHDS-negative LCMV WE strain can cause the disease, while others cannot. The genetic basis of this phenotypic difference is a nucleotide substitution resulting in a single amino acid difference in the viral glycoprotein. Reassortant studies indicate that the single amino acid substitution (Ser-153 to Phe) is sufficient to allow infection of the GH-producing cells and cause GHDS. These results show that a single change in the genome can affect viral pathogenicity by altering the tropism of the virus.

Tough DF, Borrow P, Sprent J. 1996. Induction of bystander T cell proliferation by viruses and type I interferon in vivo. Science, 272 (5270), pp. 1947-1950. | Show Abstract | Read more

T cell proliferation in vivo is presumed to reflect a T cell receptor (TCR)-mediated polyclonal response directed to various environmental antigens. However, the massive proliferation of T cells seen in viral infections is suggestive of a bystander reaction driven by cytokines instead of the TCR. In mice, T cell proliferation in viral infections preferentially affected the CD44hi subset of CD8+ cells and was mimicked by injection of polyinosinic-polycytidylic acid [poly(I:C)], an inducer of type I interferon (IFN I), and also by purified IFN I; such proliferation was not associated with up-regulation of CD69 or CD25 expression, which implies that TCR signaling was not involved. IFN I [poly(I:C)]-stimulated CD8+ cells survived for prolonged periods in vivo and displayed the same phenotype as did long-lived antigen-specific CD8+ cells. IFN I also potentiated the clonal expansion and survival of CD8+ cells responding to specific antigen. Production of IFN I may thus play an important role in the generation and maintenance of specific memory.

Guidotti LG, Borrow P, Hobbs MV, Matzke B, Gresser I, Oldstone MB, Chisari FV. 1996. Viral cross talk: intracellular inactivation of the hepatitis B virus during an unrelated viral infection of the liver. Proc Natl Acad Sci U S A, 93 (10), pp. 4589-4594. | Show Abstract | Read more

Hepatitis B virus (HBV) infection is thought to be controlled by virus-specific cytotoxic T lymphocytes (CTL). We have recently shown that HBV-specific CTL can abolish HBV replication noncytopathically in the liver of transgenic mice by secreting tumor necrosis factor alpha (TNF-alpha) and interferon gamma (IFN-gamma) after antigen recognition. We now demonstrate that hepatocellular HBV replication is also abolished noncytopathically during lymphocytic choriomeningitis virus (LCMV) infection, and we show that this process is mediated by TNF-alpha and IFN-alpha/beta produced by LCMV-infected hepatic macrophages. These results confirm the ability of these inflammatory cytokines to abolish HBV replication; they elucidate the mechanism likely to be responsible for clearance of HBV in chronically infected patients who become superinfected by other hepatotropic viruses; they suggest that pharmacological activation of intrahepatic macrophages may have therapeutic value in chronic HBV infection; and they raise the possibility that conceptually similar events may be operative in other viral infections as well.

Borrow P, Tishon A, Lee S, Xu J, Grewal IS, Oldstone MB, Flavell RA. 1996. CD40L-deficient mice show deficits in antiviral immunity and have an impaired memory CD8+ CTL response. J Exp Med, 183 (5), pp. 2129-2142. | Show Abstract | Read more

The ligand for CD40 (CD40L) is expressed on the surface of activated CD4+ T cells and its role in T-B cell collaborations and thymus-dependent humoral immunity is well established. Recently, by generating CD40L-knockout mice, we have confirmed its previously described role in humoral immunity and defined another important function of this molecule in the in vivo clonal expansion of antigen-specific CD4+ T cells. Here, we investigated the potential in vivo role of CD40L in antiviral immunity by examining the immune response mounted by CD40L-deficient mice following infection with lymphocytic choriomeningitis virus (LCMV), Pichinde virus, or vesicular stomatitis virus. Humoral immune responses of CD40L-deficient mice to these viruses were severely compromised, although moderate titres of antiviral IgM and some IgG2a were produced by virus-infected CD40L-deficient mice by a CD4+ T cell-independent mechanism. By contrast, CD40L-deficient mice made strong primary CTL responses to all three viruses. Interestingly however, although memory CTL activity was detectable in CD40L-deficient mice two months after infection with LCMV, the memory CTL response was much less efficient than in wild-type mice. Together, the results show that CD40-CD40L interactions are required for strong antiviral humoral immune responses, and reveal a novel role for CD40L in the establishment and/or maintenance of CD8+ CTL memory.

Oldstone MB, Lewicki H, Borrow P, Hudrisier D, Gairin JE. 1995. Discriminated selection among viral peptides with the appropriate anchor residues: implications for the size of the cytotoxic T-lymphocyte repertoire and control of viral infection. J Virol, 69 (12), pp. 7423-7429. | Show Abstract

Structural characterization of peptides restricted by major histocompatibility complex (MHC) class I molecules has identified residues critical for MHC class I binding and for T-cell receptor recognition. For example, optimal peptides fitting into the murine MHC class I Db groove are 9 to 11 amino acids long and require as MHC anchor residues an Asn (N) at position 5 and also either a hydrophobic residue, a Met (M) or a Cys (C), at the carboxy terminus. The three known Db-restricted peptides of lymphocytic choriomeningitis virus (LCMV) are glycoproteins GP1 (amino acids [aa] 33 KAVYNFATC), GP2 (aa 276 SGVENPGGYCL), and nucleoprotein NP (aa 396 FQPQNGQFI). In addition to these two GP and one NP peptides, computer search revealed 11 other GP peptide sequences and 20 additional NP sequences that contained the Db binding motif. By Db competitive binding analysis, only two of these 11 GP peptides and 1 of these 20 NP peptides bound to the MHC Db molecule with an affinity equivalent to the measured affinities for the three known GP1, GP2, and NP cytotoxic T-lymphocyte (CTL) epitopes. No CTL specific for these three peptides were generated when H-2b mice were inoculated with viral variants in which either the two known GP epitopes (GP1 and GP2; termed GPV) or the GPV and NP epitopes (termed GPV + NPV) were mutated. However, a novel CD8+ anti-LCMV CTL response ordinarily not seen in H-2b mice inoculated with wild-type virus was noted when such mice were inoculated with the GPV + NPV-mutated variant. This result indicates that (i) despite large numbers of peptides containing the appropriate anchor residues within a viral protein, only a restricted number induce CTL, thereby maintaining a limited CTL repertoire, (ii) despite the limited repertoire, the immune system retains the flexibility to generate an immune response(s) to a previously silent protein(s), suggesting a hierarchial control mechanism, and (iii) identification of a primary amino acid sequence is not sufficient, per se, to predict CTL epitopes, and peptide conformations are likely more complex than indicated by simple linear sequence comparisons.

Borrow P, Cornell JL, Ruppe MD, Mucke L. 1995. Immunization-induced inflammatory infiltration of the central nervous system in transgenic mice expressing a microbial antigen in astrocytes. J Neuroimmunol, 61 (2), pp. 133-149. | Show Abstract | Read more

Transgenic mice expressing a defined microbial antigen from central nervous system (CNS) cell type-specific promoters can be utilized to investigate the consequences of induction of peripheral immune responses to foreign antigens produced by different CNS cell types. Immunization of mice expressing beta-galactosidase (beta-gal) in astrocytes with this protein resulted in antigen-dependent infiltration of the CNS by mononuclear cells, principally CD4+ T lymphocytes and monocyte/macrophages. The perivascular and intraparenchymal infiltrates, which were located predominantly in the hippocampal formation and cerebellum, the areas of highest beta-gal expression, were associated with astrocytosis, microgliosis, and a generalized increase in blood-brain barrier permeability. The resemblance of these pathological changes to aspects of human immune inflammatory CNS disorders, e.g. multiple sclerosis, suggests that an initiating step in the process by which such complex diseases are produced could be the induction of peripheral immune responses to antigens expressed in astrocytes.

Lewicki H, Tishon A, Borrow P, Evans CF, Gairin JE, Hahn KM, Jewell DA, Wilson IA, Oldstone MB. 1995. CTL escape viral variants. I. Generation and molecular characterization. Virology, 210 (1), pp. 29-40. | Show Abstract | Read more

Cytotoxic T lymphocytes (CTL) play a pivotal role in preventing persistent viral infections and aborting acute infections. H-2Db-restricted CTL optimally recognize a specific peptide of 9 to 11 amino acids (aa) derived from a viral protein and held in place (restricted) by a MHC class I glycoprotein on the surfaces of infected cells. Only three peptide sequences with the appropriate Db motif from lymphocytic choriomeningitis virus Armstrong strain (LCMV) are known to be presented to CTL by H-2Db molecules; they are from the glycoproteins (GP), residues 33-41 KAVYNFATC (GP1) and 276-286 SGVENPGGYCL (GP2), and the nucleoprotein (NP), 396-404 FQPQNGQFI. Incubation of virally infected H-2b cells with CTL clones that recognize only GP1, GP2, or NP leads to the selection of viral variants which upon infecting cells bearing H-2b molecules, escape recognition by CTL of the appropriate specificity. Nucleic acid sequencing showed a single mutation in GP1 (aa 38 F-->L), GP2 (aa 282 G-->D), or NP (aa 403 F-->L) in the variant viruses. When wild-type (wt) LCMV peptides and the three variant peptides (GP1, GP2, NP) were synthesized and subjected to a competitive inhibition binding assay, no differences in binding affinity for H-2Db were found between the wt and variant peptides. Uninfected cells coated with the wt peptide were recognized and lysed by the appropriate CTL clone or by in vivo-primed bulk CTL, but similar targets coated with the GP1, GP2, or NP variant peptides were not. This result, coupled with computer graphic analysis of these variant peptides with the recently solved three-dimensional structure for the Db MHC class I molecule, placed the side chain of the mutated residues on the outer surface of the MHC-peptide complex and accessible to the T cell receptor. Ala substitution at GP residue 38 or 282 or at NP 403 also abrogated CTL recognition and lysis. Inoculation of any one of the mutated viral variants into mice produced an effective CTL response to the other two nonmutated GP or NP peptides, suggesting that production of biologically relevant CTL escape virus variants in vivo requires selection of mutations in more than one and likely all the CTL epitopes, a low probability event.

TOUGH D, BORROW P, SPRENT J. 1995. BYSTANDER PROLIFERATION OF CD8+ T-CELLS IN-VIVO JOURNAL OF CELLULAR BIOCHEMISTRY, pp. 131-131.

Borrow P, Evans CF, Oldstone MB. 1995. Virus-induced immunosuppression: immune system-mediated destruction of virus-infected dendritic cells results in generalized immune suppression. J Virol, 69 (2), pp. 1059-1070. | Show Abstract

Despite the clinical importance of virus-induced immunosuppression, how virus infection may lead to a generalized suppression of the host immune response is poorly understood. To elucidate the principles involved, we analyzed the mechanism by which a lymphocytic choriomeningitis virus (LCMV) variant produces a generalized immune suppression in its natural host, the mouse. Whereas adult mice inoculated intravenously with LCMV Armstrong rapidly clear the infection and remain immunocompetent, inoculation with the Armstrong-derived LCMV variant clone 13, which differs from its parent virus at only two amino acid positions, by contrast results in persistent infection and a generalized deficit in responsiveness to subsequent immune challenge. Here we show that the immune suppression induced by LCMV clone 13 is associated with a CD8-dependent loss of interdigitating dendritic cells from periarteriolar lymphoid sheaths in the spleen and, functionally, with a deficit in the ability of splenocytes from infected mice to stimulate the proliferation of naive T cells in a primary mixed lymphocyte reaction. Dendritic cells are not depleted in immunocompetent Armstrong-infected mice. LCMV Armstrong and clone 13 exhibit differences in their tropism within the spleen, with clone 13 causing a higher level of infection of antigen-presenting cells in the white pulp, including periarterial interdigitating dendritic cells, than Armstrong, thereby rendering these cells targets for destruction by the antiviral CD8+ cytotoxic T-lymphocyte response which is induced at early times following infection with either virus. Our findings illustrate the key role that virus tropism may play in determining pathogenicity and, further, document a mechanism for virus-induced immunosuppression which may contribute to the clinically important immune suppression associated with many virus infections, including human immunodeficiency virus type 1.

BORROW P, LEWICKI H, HORWITZ M, HAHN B, SHAW G, OLDSTONE M. 1995. ANALYSIS OF THE ANTIVIRAL CYTOTOXIC T-LYMPHOCYTE RESPONSE IN PRIMARY HIV-1 JOURNAL OF CELLULAR BIOCHEMISTRY, pp. 309-309.

Borrow P, Oldstone MB. 1995. Measles virus-mononuclear cell interactions. Curr Top Microbiol Immunol, 191 pp. 85-100.

Evans CF, Borrow P, de la Torre JC, Oldstone MB. 1994. Virus-induced immunosuppression: kinetic analysis of the selection of a mutation associated with viral persistence. J Virol, 68 (11), pp. 7367-7373. | Show Abstract

Infection of neonatal mice with lymphocytic choriomeningitis virus (LCMV) strain Armstrong (ARM) results in a lifelong persistent infection. Viral variants (cytotoxic T lymphocyte [CTL] negative, persistence positive [CTL- P+]) can be isolated from the lymphoid tissues of such mice. Adult mice inoculated with these CTL- P+ viruses fail to generate sufficient cytotoxic T lymphocytes to clear the acute infection and become persistently infected. By contrast, inoculation of a similar dose of the parental ARM virus (CTL+ P-) into adult mice leads to the generation of a vigorous virus-specific CTL response that clears the infection. Sequence analysis revealed a phenylalanine (Phe)-to-Leucine (Leu) change at amino acid 260 of the viral glycoprotein (GP) as a marker for variant viruses with the CTL- P+ phenotype. An RNA PCR assay that detects the variant GP sequence and thus allows kinetic studies of the selection of the Leu at position 260 was developed. We found that although CTL- P+ viruses are known to be lymphotropic, mature T and B cells were not required for the generation and selection of the Leu at GP amino acid 260. Kinetically, in mice infected at birth with LCMV ARM, as early as 3 weeks postinfection the Phe-to-Leu change was found in virus in the serum. By 5 weeks, viral nucleic acid obtained from peritoneal macrophages, spleen, lymph nodes, and liver showed the Phe-to-Leu change. At 2 months postinfection, the Leu change was detected in virus from the thymus, heart, lung, and kidney. By contrast, virus replicating in the central nervous system showed only minimal levels of the Leu change by 4 months and as long as 1 year postinfection. In vitro studies showed that the parental LCMV ARM CTL+ P- virus replicates more efficiently and outcompetes CTL- P+ virus in a cultured neuronal cell line, indicating that differential growth properties in neurons are likely the basis for the selection of the parental virus over the CTL- P+ variant in the brain.

Borrow P, Lewicki H, Hahn BH, Shaw GM, Oldstone MB. 1994. Virus-specific CD8+ cytotoxic T-lymphocyte activity associated with control of viremia in primary human immunodeficiency virus type 1 infection. J Virol, 68 (9), pp. 6103-6110. | Show Abstract

Human immunodeficiency virus type 1 (HIV-1) Env-, Gag-, Pol-, Nef-, and Tat-specific cytotoxic T-lymphocyte (CTL) activities were quantitated temporally in five patients with symptomatic primary HIV-1 infection. A dominant CD8(+)-mediated, major histocompatibility complex class I-restricted CTL response to the HIV-1 envelope glycoprotein, gp160, was noted in four of the five patients studied. The level of HIV-1-specific CTL activity in the five patients paralleled the efficiency of control of primary viremia. Patients who mounted strong gp160-specific CTL responses showed rapid reduction of acute plasma viremia and antigenemia, while in contrast, primary viremia and antigenemia were poorly controlled in patients in whom virus-specific CTL activity was low or undetectable. These results suggest that HIV-1-specific CTL activity is a major component of the host immune response associated with the control of virus replication following primary HIV-1 infection and have important implications for the design of antiviral vaccines.

Pantaleo G, Demarest JF, Soudeyns H, Graziosi C, Denis F, Adelsberger JW, Borrow P, Saag MS, Shaw GM, Sekaly RP. 1994. Major expansion of CD8+ T cells with a predominant V beta usage during the primary immune response to HIV. Nature, 370 (6489), pp. 463-467. | Show Abstract | Read more

A SIGNIFICANT proportion (up to 70%) of individuals experience an acute clinical syndrome of varying severity associated with primary infection with the human immunodeficiency virus (HIV). We report here studies on six individuals who showed an acute HIV syndrome which generally resolved within four weeks, concomitant with a dramatic downregulation of viraemia. To characterize the T-cell-mediated primary immune response to HIV, we used combined semiquantitative polymerase chain reaction assay and cytofluorometry to analyse the T-cell antigen receptor repertoire in sequential peripheral blood mononuclear cells from the patients. We found major oligoclonal expansions in a restricted set of variable-domain beta-chain (V beta) families. Cells expressing the expanded V beta s predominantly expressed the CD8 T-cell differentiation antigen and mediated HIV-specific cytotoxicity. Major oligoclonal expansions of these CD8+ T lymphocytes may represent an important component of the primary immune response to viral infections and may help to clarify both the immunopathogenic and the protective mechanisms of HIV infection.

Borrow P, Oldstone MB. 1994. Mechanism of lymphocytic choriomeningitis virus entry into cells. Virology, 198 (1), pp. 1-9. | Show Abstract | Read more

The path that the arenavirus lymphocytic choriomeningitis virus (LCMV) uses to enter rodent fibroblastic cell lines was dissected by infectivity and inhibition studies and immunoelectron microscopy. Lysosomotropic weak bases (chloroquine and ammonium chloride) and carboxylic ionophores (monensin and nigericin) inhibited virus entry, assessed as virus nucleoprotein expression at early times post-infection, indicating that the entry process involved a pH-dependent fusion step in intracellular vesicles. That entry occurred in vesicles rather than by direct fusion of virions with the plasma membrane was confirmed by immunoelectron microscopy. The vesicles involved were large (150-300 nm diameter), smooth-walled, and not associated with clathrin. Unlike classical phagocytosis, virus uptake in these vesicles was a microfilament-independent process, as it was not blocked by cytochalasins. LCMV entry into rodent fibroblast cell lines thus involves viropexis in large smooth-walled vesicles, followed by a pH-dependent fusion event inside the cell.

BILLETER M, BELLINI W, VANBINNENDIJK R, BORROW P, BROWN F, CUTTS F, FENNELLY G, GELLIN B, GRIFFIN D, KATZ S et al. 1994. The pathogenetic aspects of measles virus infection: memorandum from a WHO meeting. Bull World Health Organ, 72 (2), pp. 199-206. | Show Abstract

Over the last three years considerable progress has been made in various areas related to measles virus and infection. A meeting to discuss the currently available data on the molecular biology of measles virus, measles immunology, immunopathology, as well as animal models for measles infection, and to identify studies that need to be carried out towards developing new vaccines was organized jointly by WHO and the U.S. National Institutes of Health and held in Montreux, Switzerland, on 20-21 April 1993. This Memorandum summarizes the discussions and recommendations made by the participants.

de la Torre JC, Rall G, Oldstone C, Sanna PP, Borrow P, Oldstone MB. 1993. Replication of lymphocytic choriomeningitis virus is restricted in terminally differentiated neurons. J Virol, 67 (12), pp. 7350-7359. | Show Abstract

We have investigated the replication of lymphocytic choriomeningitis virus (LCMV) before and after the nerve growth factor (NGF)-induced transdifferentiation of PC12 cells from the chromaffin to the neuron-like phenotype. Untreated and NGF-treated cells were equally susceptible to LCMV infection; however, the viral yield was found to be 1,000-fold lower in NGF-differentiated PC12 cells. The reduced viral yield correlated with restricted LCMV replication and transcription within the infected cell, which was not caused by the lack of cell proliferation in the NGF-treated cells but rather was related to the induction or changes in expression levels of specific gene product(s) associated with the cell commitment to a neuronal phenotype. The return to the chromaffin phenotype after withdrawal of NGF restored normal LCMV yields as well as levels of viral replication and transcription. The finding of reduced viral replication in terminally differentiated neuronal cells has important implications for understanding the mechanism by which neurotropic viruses, such as LCMV, are able to establish a long-term persistent infection in the central nervous system in the absence of severe pathological changes.

Borrow P, Welsh CJ, Nash AA. 1993. Study of the mechanisms by which CD4+ T cells contribute to protection in Theiler's murine encephalomyelitis. Immunology, 80 (3), pp. 502-506. | Show Abstract

Theiler's murine encephalomyelitis virus (TMEV) is a picornavirus which causes a biphasic central nervous system (CNS) disease in certain strains of mice. Lytic virus replication within the CNS causes acute damage at early times post-infection, with the surviving animals developing a chronic CNS demyelinating disease. This damage is thought to result both from direct viral damage and from an immunopathological CD4+ T-cell mediated delayed-type hypersensitivity response to virus. By contrast, CD4+ T cells have a vital protective role at early times post-infection, as mice specifically depleted of CD4+ T cells of this subset prior to infection with TMEV die within 3-5 weeks. In an investigation of how CD4+ T cells act to mediate protection in TMEV-infected mice, we show that CD4+ cell-depleted animals, which fail to make a significant antiviral antibody response, could be protected by passive transfer of neutralizing antibodies. However, surviving animals had high levels of persisting virus in the CNS and they developed very severe symptoms of chronic demyelinating disease. The appearance of infectious virus was not due to selection of neutralizing antibody-resistant viral variants. These results demonstrate that the key protective role of CD4+ T cells in TMEV-infected mice is to provide help for antibody production by B cells at early times post-infection, but that other CD4+ cell-dependent mechanisms must contribute to control of virus replication, and are of importance in determining the levels of virus subsequently persisting in the CNS, and hence the severity of the chronic demyelinating disease.

Tishon A, Borrow P, Evans C, Oldstone MB. 1993. Virus-induced immunosuppression. 1. Age at infection relates to a selective or generalized defect. Virology, 195 (2), pp. 397-405. | Show Abstract | Read more

Viruses that persist must develop strategies to escape immunologic surveillance in order to survive. Investigation of lymphocytic choriomeningitis virus (LCMV)-induced persistence has indicated that this virus avoids immune clearance mainly by aborting the viral specific cytotoxic T lymphocyte (CTL) response, a response that is necessary for terminating viral infection. This study demonstrates that persistence established in immunologically immature newborns selectively depletes the LCMV-specific CTL response but does not hinder CTL responses to the RNA and DNA viruses influenza, vaccinia, or herpes simplex. In contrast, persistence established in immunologically mature adults leads not to selective but rather to generalized immunosuppression during which CTL responses to LCMV, influenza, vaccinia, and herpes simplex viruses are all ablated or down-regulated. These results indicate that the state of maturity of the immune system at the time of virus-induced immunosuppression can result in two distinct phenotypes. These observations may account for the differing patterns of infection caused by hepatitis B virus or human immunodeficiency virus initiated in the neonatal period compared to that initiated in adulthood.

EVANS C, BORROW P, OLDSTONE M. 1993. VIRUS-INDUCED IMMUNOSUPPRESSION - DIFFERENCES IN SPLENIC DESTRUCTION CAUSED BY AN IMMUNOSUPPRESSIVE VARIANT (CLONE-13) OF LCMV COMPARED TO THE NONIMMUNOSUPPRESSIVE PARENTAL VIRUS (LCMV ARM) JOURNAL OF CELLULAR BIOCHEMISTRY, pp. 55-55.

BORROW P, VEDOVATO V, BUESAGOMEZ J, DELATORRE J, OLDSTONE M. 1993. CORRELATION BETWEEN THE BINDING OF DIFFERENT ARENAVIRUSES TO PUTATIVE CELLULAR RECEPTORS INVITRO AND THEIR INVIVO PATHOGENICITY JOURNAL OF CELLULAR BIOCHEMISTRY, pp. 63-63.

Borrow P, Oldstone MB. 1992. Characterization of lymphocytic choriomeningitis virus-binding protein(s): a candidate cellular receptor for the virus. J Virol, 66 (12), pp. 7270-7281. | Show Abstract

The attachment of lymphocytic choriomeningitis virus (LCMV) to murine and primate cell lines was quantitated by a fluorescence-activated cell sorter assay in which binding of biotinylated virus was detected with streptavidin-fluorescein isothiocyanate. Cell lines that were readily infected by LCMV (e.g., MC57, Rin, BHK, Vero, and HeLa) bound virus in a dose-dependent manner, whereas no significant binding was observed to lymphocytic cell lines (e.g., RMA and WIL 2) that were not readily infected. Binding was specific and competitively blocked by nonbiotinylated LCMV. It was also blocked by LCMV-specific antiserum and a neutralizing monoclonal antibody to the virus glycoprotein GP-1 but not by antibodies specific for GP-2, indicating that attachment was likely mediated by GP-1. Treatment of cells with any of several proteases abolished LCMV binding, whereas phospholipases including phosphatidylinositol-specific phospholipase C had no effect, indicating that one or more membrane proteins were involved in virus attachment. These proteins were characterized with a virus overlay protein blot assay. Virus bound to protein(s) with a molecular mass of 120 to 140 kDa in membranes from cell lines permissive for LCMV but not from nonpermissive cell lines. Binding was specific, since unlabeled LCMV, but not the unrelated enveloped virus herpes simplex virus type 1, competed with 125I-labeled LCMV for binding to the 120- to 140-kDa band. The proteinaceous nature of the LCMV-binding substance was confirmed by the lack of virus binding to proteinase K-treated membrane components. By contrast, glycosidase treatment of membranes did not abolish virus binding. However, in membranes treated with endoglycosidase F/N-glycosidase F, and/or neuraminidase and in membranes from cells grown in tunicamycin, the molecular mass of the LCMV-binding entity was reduced. Hence, LCMV attachment to rodent fibroblastic cell lines is mediated by a glycoprotein(s) with a molecular mass of 120 to 140 kDa, with complex N-linked sugars that are not involved in virus binding.

Borrow P, Tonks P, Welsh CJ, Nash AA. 1992. The role of CD8+T cells in the acute and chronic phases of Theiler's murine encephalomyelitis virus-induced disease in mice. J Gen Virol, 73 ( Pt 7) (7), pp. 1861-1865. | Show Abstract | Read more

The technique of in vivo depletion with T cell subset-specific monoclonal antibodies was used to study the involvement of CD8+T cells in protection/pathogenesis during the acute and chronic demyelinating phases of Theiler's murine encephalomyelitis virus (TMEV)-induced disease. Mice rendered CD8-deficient prior to infection with TMEV were less efficient at clearing virus from the central nervous system compared to intact animals and also suffered demyelinating disease of earlier onset and increased severity. This indicates that CD8+ cells have a protective role in virus clearance at early times post-infection, and may also be involved in downregulating the severity of the chronic demyelinating disease. How CD8+ T cells function to produce these effects is discussed.

Borrow P, Nash AA. 1992. Susceptibility to Theiler's virus-induced demyelinating disease correlates with astrocyte class II induction and antigen presentation. Immunology, 76 (1), pp. 133-139. | Show Abstract

Theiler's murine encephalomyelitis virus (TMEV) is a picornavirus which induces a chronic demyelinating disease of the central nervous system (CNS) in certain susceptible mouse strains. Demyelination has been shown to result from immunopathological responses mediated by CD4+, major histocompatibility complex (MHC) class II-restricted T cells. As little or no class II is expressed in the normal mouse CNS, the ability of astrocytes to express these proteins and present antigen to T cells from TMEV-infected mice was investigated here. It is shown that astrocytes are capable of presenting TMEV to virus-specific T cells in vitro, and that this ability is dependent on prior induction of MHC class II by interferon-gamma (IFN-gamma) treatment. Unlike other viruses such as murine hepatitis virus-JHM (a coronavirus) and measles, TMEV is not capable of inducing class II on astrocytes directly. There is a correlation between the ease of class II induction on astrocytes from different mouse strains by IFN-gamma and mouse strain susceptibility to TMEV-induced demyelinating disease. These results suggest that following viral infection and initial T-cell infiltration into the CNS, class II induction on astrocytes is a key step allowing local antigen presentation and amplification of immunopathological responses within the CNS and hence the development of demyelinating disease.

de la Torre JC, Borrow P, Oldstone MB. 1991. Viral persistence and disease: cytopathology in the absence of cytolysis. Br Med Bull, 47 (4), pp. 838-851. | Show Abstract | Read more

Realising that viruses could persist and thereby cause chronic disease has been one of the major accomplishments in virology. In this review we will discuss the principles by which viruses can persist and how such persistence can lead to disease. Our focus will be on the ability of certain viruses to interfere subtly with the cell's ability to produce specific differentiated products as hormones, neurotransmitters, cytokines and immunoglobulins, etc., in the absence of their ability to lyse the cell they infect. By this means viruses can replicate in histologically normal appearing cells and tissues. Despite viral replication the infected cell maintains its normal anatomic architecture and yet the virus disorders the differentiated or luxury function of the cell leading to disturbances in homeostasis and disease. Viruses by this means likely underline a wide variety of clinical illnesses, currently of unknown aetiology, that affect the endocrine, immune, nervous and other differentiated systems.

Borrow P, Tishon A, Oldstone MB. 1991. Infection of lymphocytes by a virus that aborts cytotoxic T lymphocyte activity and establishes persistent infection. J Exp Med, 174 (1), pp. 203-212. | Show Abstract | Read more

For viruses to establish persistent infections in their hosts, they must possess some mechanism for evading clearance by the immune system. When inoculated into adult immunocompetent mice, wild-type lymphocytic choriomeningitis virus (LCMV ARM) induces a CD8(+)-mediated cytotoxic T lymphocyte (CTL) response that clears the infection within 7-14 d (CTL+ [P-]). By contrast, variant viruses isolated from lymphoid tissues of persistently infected mice fail to induce a CTL response and are thus able to establish a persistent infection in adult mice (CTL- [P+]). This report compares the interaction of CTL+ (P-) and CTL- (P+) viruses with cells of the immune system. Both types of virus initially bind to 2-4% of CD4+ and CD8+ T lymphocytes and replicate within cells of both subsets. The replication of CTL- (P+) and CTL+ (P-) viruses in lymphocytes in vivo is similar for the first 5 d after initiating infection. Thereafter, in mice infected with CTL- (P+) variants, lymphocytes retain viral genetic information, and infectious virus can be recovered throughout the animals' lives. In contrast, when adult mice are infected with wild-type CTL+ (P-) LCMV ARM, virus is not recovered from lymphocytes for greater than 7 d after infection. A CD8(+)-mediated anti-LCMV CTL response is induced in such mice. Clearance of infected lymphocytes is produced by these LCMV-specific CTLs, as shown by their ability to lyse lymphocytes expressing LCMV determinants in vitro and the fact that depletion of CD8+ lymphocytes before infection with CTL+ (P-) viruses results in levels of infected lymphocytes similar to those found in undepleted CTL- (P+)-infected mice. Hence, CTL-mediated lysis of T lymphocytes carrying infectious virus is a critical factor determining whether virus persists or the infection is terminated.

Salvato M, Borrow P, Shimomaye E, Oldstone MB. 1991. Molecular basis of viral persistence: a single amino acid change in the glycoprotein of lymphocytic choriomeningitis virus is associated with suppression of the antiviral cytotoxic T-lymphocyte response and establishment of persistence. J Virol, 65 (4), pp. 1863-1869. | Show Abstract

Isolates of lymphocytic choriomeningitis virus (LCMV) that elicit a cytotoxic T-lymphocyte response (CTL+) have been compared with isolates that suppress the CTL response (CTL-) in an effort to map this phenotype. A single amino acid change in the glycoprotein of the LCMV Armstrong (ARM) strain is consistently associated with the CTL- trait and the ability of the virus to persist (P+). The CTL+ P- parental strain spontaneously gives rise to CTL- P+ variants within lymphoid tissues of mice persistently infected from birth. To map the structural basis of the phenotype, the complete RNA sequence of LCMV ARM 53b (CTL+) was compared with that of its variant ARM clone 13 (CTL-). Differences in 5 of 10,600 nucleotides were found. Three changes are noted in the large L RNA segment, and two are noted in the small S RNA segment. Only two of the changes distinguishing CTL+ from CTL- isolates affect amino acid coding: lysine to glutamine at amino acid 1079 of the polymerase protein, and phenylalanine to leucine at amino acid 260 of the envelope glycoprotein (GP). We also analyzed two additional CTL- variants and four spontaneous CTL+ revertants. All three CTL- variants differ from the original CTL+ parental strain at GP amino acid 260, indicating that this amino acid change is consistently associated with the CTL- phenotype. By contrast the other four mutations in LCMV are not associated with the CTL- phenotype. Sequence analysis of the coding regions of four CTL+ revertants of ARM clone 13 did not reveal back mutations at the GP 260 locus. This finding indicates that the GP 260 mutation is necessary but not sufficient for a CTL- P+ phenotype and that the reversion to CTL+ P- is likely either due to secondary mutations in other regions of the viral genome or to quasispecies within the revertant population that make significant contributions to the phenotype.

Welsh CJ, Tonks P, Borrow P, Nash AA. 1990. Theiler's virus: an experimental model of virus-induced demyelination. Autoimmunity, 6 (1-2), pp. 105-112. | Read more

Abbott RJ, Pachnio A, Pedroza-Pacheco I, Leese AM, Begum J, Long HM, Croom-Carter D, Stacey A, Moss PAH, Hislop AD et al. 2017. Asymptomatic primary infection with Epstein-Barr virus: observations on young adult cases. J Virol, pp. JVI.00382-17-JVI.00382-17. | Show Abstract | Read more

Epstein-Barr virus (EBV) is typically acquired asymptomatically in childhood. By contrast, infection later in life often leads to infectious mononucleosis (IM), a febrile illness characterised by anti-EBV IgM antibody-positivity, high loads of circulating latently-infected B cells, and a marked lymphocytosis caused by hyper-expansion of EBV-specific CD8(+) T cells plus milder expansion of CD56(dim) NKG2A(+) KIR(-) NK cells. How the two situations compare is unclear due to the paucity of studies on clinically-silent infection. Here we describe five prospectively-studied asymptomatic infections identified in a sero-epidemiological survey of University entrants. In each case the key blood sample had high cell-associated viral loads without marked IM-like CD8 lymphocytosis or NK cell disturbance. Two of the highest viral load cases showed a coincident expansion of activated EBV-specific CD8(+) T cells but overall CD8(+) T cell numbers were either unaffected or only mildly increased. Two slightly lower load cases, which serology suggests may have been caught earlier in the course of infection, also showed no T or NK cell expansion at the time. Interestingly, in another higher load case where T and NK cell responses were undetectable in the primary infection bleed, EBV-specific T cell responses did not appear until several months later, by which time virus loads in the blood had already fallen. Thus some asymptomatic primary infections have very high circulating viral loads and a cell-mediated immune response that is qualitatively similar to IM but of lower magnitude. However, others may be quite different and ultimately could reveal novel mechanisms of host control.IMPORTANCE Epstein-Barr virus (EBV) is transmitted orally, replicates in the throat and then invades the B lymphocyte pool through a growth-transforming latent infection. While primary infection in childhood is usually asymptomatic, delayed infection is associated with infectious mononucleosis (IM), a febrile illness with high circulating viral loads and an exaggerated virus-induced immune response involving both CD8(+) T cells and natural-killer (NK) cells. Here we show that in five cases of asymptomatic infection, virus loads in the blood are as high as in acute IM whereas cell-mediated responses, even where they resemble IM in timing and quality, are never as exaggerated. We infer that IM symptoms arise as a consequence not of the virus infection per se, but of the hyper-activated immune response. Interestingly, there were idiosyncratic differences among asymptomatic cases in the relationship between viral load and response kinetics, emphasising how much there is still to learn about primary EBV infection.

Foster TL, Wilson H, Iyer SS, Coss K, Doores K, Smith S, Kellam P, Finzi A, Borrow P, Hahn BH, Neil SJD. 2016. Resistance of Transmitted Founder HIV-1 to IFITM-Mediated Restriction. Cell Host Microbe, 20 (4), pp. 429-442. | Show Abstract | Read more

Interferon-induced transmembrane proteins (IFITMs) restrict the entry of diverse enveloped viruses through incompletely understood mechanisms. While IFITMs are reported to inhibit HIV-1, their in vivo relevance is unclear. We show that IFITM sensitivity of HIV-1 strains is determined by the co-receptor usage of the viral envelope glycoproteins as well as IFITM subcellular localization within the target cell. Importantly, we find that transmitted founder HIV-1, which establishes de novo infections, is uniquely resistant to the antiviral activity of IFITMs. However, viral sensitivity to IFITMs, particularly IFITM2 and IFITM3, increases over the first 6 months of infection, primarily as a result of neutralizing antibody escape mutations. Additionally, the ability to evade IFITM restriction contributes to the different interferon sensitivities of transmitted founder and chronic viruses. Together, these data indicate that IFITMs constitute an important barrier to HIV-1 transmission and that escape from adaptive immune responses exposes the virus to antiviral restriction.

Moody MA, Pedroza-Pacheco I, Vandergrift NA, Chui C, Lloyd KE, Parks R, Soderberg KA, Ogbe AT, Cohen MS, Liao HX et al. 2016. Immune perturbations in HIV-1-infected individuals who make broadly neutralizing antibodies. Sci Immunol, 1 (1), pp. aag0851. | Show Abstract | Read more

Induction of broadly neutralizing antibodies (bnAbs) is a goal of HIV-1 vaccine development. bnAbs occur in some HIV-1-infected individuals and frequently have characteristics of autoantibodies. We have studied cohorts of HIV-1-infected individuals who made bnAbs and compared them with those who did not do so, and determined immune traits associated with the ability to produce bnAbs. HIV-1-infected individuals with bnAbs had a higher frequency of blood autoantibodies, a lower frequency of regulatory CD4(+) T cells, a higher frequency of circulating memory T follicular helper CD4(+) cells, and a higher T regulatory cell level of programmed cell death-1 expression compared with HIV-1-infected individuals without bnAbs. Thus, induction of HIV-1 bnAbs may require vaccination regimens that transiently mimic immunologic perturbations in HIV-1-infected individuals.

Haynes BF, Shaw GM, Korber B, Kelsoe G, Sodroski J, Hahn BH, Borrow P, McMichael AJ. 2016. HIV-Host Interactions: Implications for Vaccine Design. Cell Host Microbe, 19 (3), pp. 292-303. | Show Abstract | Read more

Development of an effective AIDS vaccine is a global priority. However, the extreme diversity of HIV type 1 (HIV-1), which is a consequence of its propensity to mutate to escape immune responses, along with host factors that prevent the elicitation of protective immune responses, continue to hinder vaccine development. Breakthroughs in understanding of the biology of the transmitted virus, the structure and nature of its envelope trimer, vaccine-induced CD8 T cell control in primates, and host control of broadly neutralizing antibody elicitation have given rise to new vaccine strategies. Despite this promise, emerging data from preclinical trials reinforce the need for additional insight into virus-host biology in order to facilitate the development of a successful vaccine.

Bridgeman A, Maelfait J, Davenne T, Partridge T, Peng Y, Mayer A, Dong T, Kaever V, Borrow P, Rehwinkel J. 2015. Viruses transfer the antiviral second messenger cGAMP between cells. Science, 349 (6253), pp. 1228-1232. | Show Abstract | Read more

Cyclic GMP-AMP synthase (cGAS) detects cytosolic DNA during virus infection and induces an antiviral state. cGAS signals by synthesis of a second messenger, cyclic GMP-AMP (cGAMP), which activates stimulator of interferon genes (STING). We show that cGAMP is incorporated into viral particles, including lentivirus and herpesvirus virions, when these are produced in cGAS-expressing cells. Virions transferred cGAMP to newly infected cells and triggered a STING-dependent antiviral program. These effects were independent of exosomes and viral nucleic acids. Our results reveal a way by which a signal for innate immunity is transferred between cells, potentially accelerating and broadening antiviral responses. Moreover, infection of dendritic cells with cGAMP-loaded lentiviruses enhanced their activation. Loading viral vectors with cGAMP therefore holds promise for vaccine development.

Yue L, Pfafferott KJ, Baalwa J, Conrod K, Dong CC, Chui C, Rong R, Claiborne DT, Prince JL, Tang J et al. 2015. Transmitted virus fitness and host T cell responses collectively define divergent infection outcomes in two HIV-1 recipients. PLoS Pathog, 11 (1), pp. e1004565. | Show Abstract | Read more

Control of virus replication in HIV-1 infection is critical to delaying disease progression. While cellular immune responses are a key determinant of control, relatively little is known about the contribution of the infecting virus to this process. To gain insight into this interplay between virus and host in viral control, we conducted a detailed analysis of two heterosexual HIV-1 subtype A transmission pairs in which female recipients sharing three HLA class I alleles exhibited contrasting clinical outcomes: R880F controlled virus replication while R463F experienced high viral loads and rapid disease progression. Near full-length single genome amplification defined the infecting transmitted/founder (T/F) virus proteome and subsequent sequence evolution over the first year of infection for both acutely infected recipients. T/F virus replicative capacities were compared in vitro, while the development of the earliest cellular immune response was defined using autologous virus sequence-based peptides. The R880F T/F virus replicated significantly slower in vitro than that transmitted to R463F. While neutralizing antibody responses were similar in both subjects, during acute infection R880F mounted a broad T cell response, the most dominant components of which targeted epitopes from which escape was limited. In contrast, the primary HIV-specific T cell response in R463F was focused on just two epitopes, one of which rapidly escaped. This comprehensive study highlights both the importance of the contribution of the lower replication capacity of the transmitted/founder virus and an associated induction of a broad primary HIV-specific T cell response, which was not undermined by rapid epitope escape, to long-term viral control in HIV-1 infection. It underscores the importance of the earliest CD8 T cell response targeting regions of the virus proteome that cannot mutate without a high fitness cost, further emphasizing the need for vaccines that elicit a breadth of T cell responses to conserved viral epitopes.

Armitage AE, Stacey AR, Giannoulatou E, Marshall E, Sturges P, Chatha K, Smith NM, Huang X, Xu X, Pasricha SR et al. 2014. Distinct patterns of hepcidin and iron regulation during HIV-1, HBV, and HCV infections. Proc Natl Acad Sci U S A, 111 (33), pp. 12187-12192. | Show Abstract | Read more

During HIV type-1 (HIV-1), hepatitis C virus (HCV), and hepatitis B virus (HBV) infections, altered iron balance correlates with morbidity. The liver-produced hormone hepcidin dictates systemic iron homeostasis. We measured hepcidin, iron parameters, cytokines, and inflammatory markers in three cohorts: plasma donors who developed acute HIV-1, HBV, or HCV viremia during the course of donations; HIV-1-positive individuals progressing from early to chronic infection; and chronically HIV-1-infected individuals (receiving antiretroviral therapy or untreated). Hepcidin increased and plasma iron decreased during acute HIV-1 infection, as viremia was initially detected. In patients transitioning from early to chronic HIV-1 infection, hepcidin in the first 60 d of infection positively correlated with the later plasma viral load set-point. Hepcidin remained elevated in individuals with untreated chronic HIV-1 infection and in subjects on ART. In contrast to HIV-1, there was no evidence of hepcidin up-regulation or hypoferremia during the primary viremic phases of HCV or HBV infection; serum iron marginally increased during acute HBV infection. In conclusion, hepcidin induction is part of the pathogenically important systemic inflammatory cascade triggered during HIV-1 infection and may contribute to the establishment and maintenance of viral set-point, which is a strong predictor of progression to AIDS and death. However, distinct patterns of hepcidin and iron regulation occur during different viral infections that have particular tissue tropisms and elicit different systemic inflammatory responses. The hypoferremia of acute infection is therefore a pathogen-specific, not universal, phenomenon.

Fenton-May AE, Dibben O, Emmerich T, Ding H, Pfafferott K, Aasa-Chapman MM, Pellegrino P, Williams I, Cohen MS, Gao F et al. 2013. Relative resistance of HIV-1 founder viruses to control by interferon-alpha. Retrovirology, 10 (1), pp. 146. | Show Abstract | Read more

BACKGROUND: Following mucosal human immunodeficiency virus type 1 (HIV-1) transmission, type 1 interferons (IFNs) are rapidly induced at sites of initial virus replication in the mucosa and draining lymph nodes. However, the role played by IFN-stimulated antiviral activity in restricting HIV-1 replication during the initial stages of infection is not clear. We hypothesized that if type 1 IFNs exert selective pressure on HIV-1 replication in the earliest stages of infection, the founder viruses that succeed in establishing systemic infection would be more IFN-resistant than viruses replicating during chronic infection, when type 1 IFNs are produced at much lower levels. To address this hypothesis, the relative resistance of virus isolates derived from HIV-1-infected individuals during acute and chronic infection to control by type 1 IFNs was analysed. RESULTS: The replication of plasma virus isolates generated from subjects acutely infected with HIV-1 and molecularly cloned founder HIV-1 strains could be reduced but not fully suppressed by type 1 IFNs in vitro. The mean IC50 value for IFNα2 (22 U/ml) was lower than that for IFNβ (346 U/ml), although at maximally-inhibitory concentrations both IFN subtypes inhibited virus replication to similar extents. Individual virus isolates exhibited differential susceptibility to inhibition by IFNα2 and IFNβ, likely reflecting variation in resistance to differentially up-regulated IFN-stimulated genes. Virus isolates from subjects acutely infected with HIV-1 were significantly more resistant to in vitro control by IFNα than virus isolates generated from the same individuals during chronic, asymptomatic infection. Viral IFN resistance declined rapidly after the acute phase of infection: in five subjects, viruses derived from six-month consensus molecular clones were significantly more sensitive to the antiviral effects of IFNs than the corresponding founder viruses. CONCLUSIONS: The establishment of systemic HIV-1 infection by relatively IFNα-resistant founder viruses lends strong support to the hypothesis that IFNα plays an important role in the control of HIV-1 replication during the earliest stages of infection, prior to systemic viral spread. These findings suggest that it may be possible to harness the antiviral activity of type 1 IFNs in prophylactic and potentially also therapeutic strategies to combat HIV-1 infection.

Ribeiro-dos-Santos P, Turnbull EL, Monteiro M, Legrand A, Conrod K, Baalwa J, Pellegrino P, Shaw GM, Williams I, Borrow P, Rocha B. 2012. Chronic HIV infection affects the expression of the 2 transcription factors required for CD8 T-cell differentiation into cytolytic effectors. Blood, 119 (21), pp. 4928-4938. | Show Abstract | Read more

CD8 T cells lose the capacity to control HIV infection, but the extent of the impairment of CD8 T-cell functions and the mechanisms that underlie it remain controversial. Here we report an extensive ex vivo analysis of HIV-specific CD8 T cells, covering the expression of 16 different molecules involved in CD8 function or differentiation. This approach gave remarkably homogeneous readouts in different donors and showed that CD8 dysfunction in chronic HIV infection was much more severe than described previously: some Ifng transcription was observed, but most cells lost the expression of all cytolytic molecules and Eomesodermin and T-bet by chronic infection. These results reveal a cellular mechanism explaining the dysfunction of CD8 T cells during chronic HIV infection, as CD8 T cells are known to maintain some functionality when either of these transcription factors is present, but to lose all cytotoxic activity when both are not expressed. Surprisingly, they also show that chronic HIV and lymphocytic choriomeningitis virus infections have a very different impact on fundamental T-cell functions, "exhausted" lymphocytic choriomeningitis virus-specific cells losing the capacity to secrete IFN-γ but maintaining some cytotoxic activity as granzyme B and FasL are overexpressed and, while down-regulating T-bet, up-regulating Eomesodermin expression.

Cited:

31

Scopus

Borrow P. 2011. Innate immunity in acute HIV-1 infection Current Opinion in HIV and AIDS, 6 (5), pp. 353-363. | Show Abstract | Read more

Purpose of review: Acute HIV-1 infection (AHI) is composed of the eclipse phase, during which the transmitted virus struggles to avoid eradication and achieve amplification/spread; the expansion phase when virus disseminates and undergoes exponential replication associated with extensive CD4 T-cell destruction; and the containment phase when set-point levels of viremia and immune activation are established. The importance of interactions between HIV-1 and innate responses in determining events throughout AHI is increasingly recognized, and is reviewed here. Recent findings: During the eclipse phase, HIV-1 subverts dendritic cell functions to promote its replication at mucosal sites and employs multiple strategies to minimize control by type 1 interferons. Systemic virus dissemination is associated with widespread activation of innate responses which fuels HIV-1 replication. To minimize the protective effects of innate responses, HIV-1 resists control by natural killer cells and may impair innate regulation of adaptive responses. Innate responses remain chronically activated after HIV-1 containment which is thought to drive HIV-1 pathogenesis. Summary: Innate responses are pivotal determinants of events at all stages of AHI. Increased understanding of mechanisms involved in innate control of HIV-1 and pathways regulating innate activation during HIV-1 infection could facilitate development of novel approaches to combating this infection. © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins.

Kramer HB, Lavender KJ, Qin L, Stacey AR, Liu MK, di Gleria K, Simmons A, Gasper-Smith N, Haynes BF, McMichael AJ et al. 2010. Elevation of intact and proteolytic fragments of acute phase proteins constitutes the earliest systemic antiviral response in HIV-1 infection. PLoS Pathog, 6 (5), pp. e1000893. | Show Abstract | Read more

The earliest immune responses activated in acute human immunodeficiency virus type 1 infection (AHI) exert a critical influence on subsequent virus spread or containment. During this time frame, components of the innate immune system such as macrophages and DCs, NK cells, beta-defensins, complement and other anti-microbial factors, which have all been implicated in modulating HIV infection, may play particularly important roles. A proteomics-based screen was performed on a cohort from whom samples were available at time points prior to the earliest positive HIV detection. The ability of selected factors found to be elevated in the plasma during AHI to inhibit HIV-1 replication was analyzed using in vitro PBMC and DC infection models. Analysis of unique plasma donor panels spanning the eclipse and viral expansion phases revealed very early alterations in plasma proteins in AHI. Induction of acute phase protein serum amyloid A (A-SAA) occurred as early as 5-7 days prior to the first detection of plasma viral RNA, considerably prior to any elevation in systemic cytokine levels. Furthermore, a proteolytic fragment of alpha-1-antitrypsin (AAT), termed virus inhibitory peptide (VIRIP), was observed in plasma coincident with viremia. Both A-SAA and VIRIP have anti-viral activity in vitro and quantitation of their plasma levels indicated that circulating concentrations are likely to be within the range of their inhibitory activity. Our results provide evidence for a first wave of host anti-viral defense occurring in the eclipse phase of AHI prior to systemic activation of other immune responses. Insights gained into the mechanism of action of acute-phase reactants and other innate molecules against HIV and how they are induced could be exploited for the future development of more efficient prophylactic vaccine strategies.

Turnbull EL, Wong M, Wang S, Wei X, Jones NA, Conrod KE, Aldam D, Turner J, Pellegrino P, Keele BF et al. 2009. Kinetics of expansion of epitope-specific T cell responses during primary HIV-1 infection. J Immunol, 182 (11), pp. 7131-7145. | Show Abstract | Read more

Multiple lines of evidence support a role for CD8(+) T cells in control of acute/early HIV replication; however, features of the primary HIV-specific CD8(+) T cell response that may impact on the efficiency of containment of early viral replication remain poorly defined. In this study, we performed a novel, comprehensive analysis of the kinetics of expansion of components of the HIV-specific CD8(+) T cell response in 21 acutely infected individuals. Epitope-specific T cell responses expanded asynchronously during primary infection in all subjects. The most rapidly expanded responses peaked as early as 5 days following symptomatic presentation and were typically of very limited epitope breadth. Responses of additional specificities expanded and contracted in subsequent waves, resulting in successive shifts in the epitope immunodominance hierarchy over time. Sequence variation and escape were temporally associated with the decline in magnitude of only a subset of T cell responses, suggesting that other factors such as Ag load and T cell exhaustion may play a role in driving the contraction of HIV-specific T cell responses. These observations document the preferential expansion of CD8(+) T cells recognizing a subset of epitopes during the viral burst in acute HIV-1 infection and suggest that the nature of the initial, very rapidly expanded T cell response may influence the efficiency with which viral replication is contained in acute/early HIV infection.

Stacey AR, Norris PJ, Qin L, Haygreen EA, Taylor E, Heitman J, Lebedeva M, DeCamp A, Li D, Grove D et al. 2009. Induction of a striking systemic cytokine cascade prior to peak viremia in acute human immunodeficiency virus type 1 infection, in contrast to more modest and delayed responses in acute hepatitis B and C virus infections. J Virol, 83 (8), pp. 3719-3733. | Show Abstract | Read more

Characterization of the immune responses induced in the initial stages of human immunodeficiency virus type 1 (HIV-1) infection is of critical importance for an understanding of early viral pathogenesis and prophylactic vaccine design. Here, we used sequential plasma samples collected during the eclipse and exponential viral expansion phases from subjects acquiring HIV-1 (or, for comparison, hepatitis B virus [HBV]or hepatitis C virus [HCV]) to determine the nature and kinetics of the earliest systemic elevations in cytokine and chemokine levels in each infection. Plasma viremia was quantitated over time, and levels of 30 cytokines and chemokines were measured using Luminex-based multiplex assays and enzyme-linked immunosorbent assays. The increase in plasma viremia in acute HIV-1 infection was found to be associated with elevations in plasma levels of multiple cytokines and chemokines, including rapid and transient elevations in alpha interferon (IFN-alpha) and interleukin-15 (IL-15) levels; a large increase in inducible protein 10 (IP-10) levels; rapid and more-sustained increases in tumor necrosis factor alpha and monocyte chemotactic protein 1 levels; more slowly initiated elevations in levels of additional proinflammatory factors including IL-6, IL-8, IL-18, and IFN-gamma; and a late-peaking increase in levels of the immunoregulatory cytokine IL-10. Notably, there was comparatively little perturbation in plasma cytokine levels during the same phase of HBV infection and a delayed response of more intermediate magnitude in acute HCV infection, indicating that the rapid activation of a striking systemic cytokine cascade is not a prerequisite for viral clearance (which occurs in a majority of HBV-infected individuals). The intense early cytokine storm in acute HIV-1 infection may have immunopathological consequences, promoting immune activation, viral replication, and CD4(+) T-cell loss.

114

Thank you for registering your interest

We were unable to record your request to register for interest in future opportunities. Please try again and if problems persist contact us at webteam@ndm.ox.ac.uk