Professor Ellie (Eleanor) Barnes
|Technology Exchange:||Bioinformatics, Cellular immunology, Flow cytometry, Gene therapy, SNP typing and Vaccine production and evaluation|
|Scientific Themes:||Immunology & Infectious Disease|
|Keywords:||Hepatitis C virus, genotype-3, T cells, vaccine, therapy, MRI, Coagulation, hepatitis E virus, Biomarkers and IgG4 systemic disease|
One of the aims of my programme is to develop a prophylactic and therapeutic hepatitis C virus vaccine (HCV). HCV is currently a global epidemic infecting 170 million people worldwide and a significant issue in the United Kingdom, where 0.4 % of the population are infected. Many chronically infected patients silently develop complications of liver disease that include hepatocellular cancer, liver cirrhosis and liver failure. Current gold-standard treatments are suboptimal, fraught with side effects and often fail.
A major challenge for HCV vaccine development is the significant viral diversity both within the same host and between hosts –though parts of the viral genome are conserved making these excellent T cell targets in the context of a T cell vaccine. Hope for a vaccine for HCV lies in the fact that after primary infection spontaneous viral eradication occurs in a significant minority of patients. The nature of the T cell response induced during this phase and HLA association studies demonstrate that T cell immunity critically affects the clinical outcome. More recently large human genome wide association studies have shown a major role for genetic polymorphisms linked to interferon-λ in both the spontaneous resolution and interferon-α induced viral eradication.
Phase-I clinical experimental vaccine studies with detailed immunological assessment are currently underway in both healthy volunteers and in HCV infected patients at the John Radcliffe Hospital, Oxford, using viral vectored approaches. Early results using simian adenoviral vectors in collaboration with Okairos show real promise. Currently we are defining the relevance of T cell responses so generated to circulating virus within the HCV infected host. This work is embedded within the Jenner Institute, and the Peter Medawar Building for Pathogen Research. The work is supported by the Medical Research council (UK) and the Oxford NIHR Biomedical Research centre.
Whilst a significant body of research has assessed T cell immunity to HCV genotype-1 infection very little is known about genotype-3a-now the dominant strain in the UK. A further focus of my laboratory related to vaccine development is the assessment of T cell immunity to genotype-3a infection in both acute infection when HCV specific T cell responses are readily detectable and in chronic infection where detection of responses often requires refined immunological techniques. Supported by the Wellcome Trust, additional work is underway to define the complex interplay between interferon-λ, interferon-α, and HCV adaptive immunity.
An exciting new programme of work to compliment the HCV vaccine programme is an assessment of the epidemiology, serology, pathogenesis and T cell immunity to hepatitis E virus infection in collaboration with Dr. Harry Dalton (Truro, Cornwall).
The finely stratified HCV cohort, and excellent supporting infrastructure through the TGU and the Oxford NIHR BRC has led to the establishment of collaborative programmes with MRI imaging and biochemistry to identify novel biomarkers of liver fibrosis. Collaborative programmes (with Vip Jairath) are also in place to assess the coagulopathy of liver disease (a highly complex process) during variceal haemorrhage with the aim of identifying novel therapeutic targets.
Other research interests include IgG4 systemic disease –a cause of severe biliary and pancreatic pathology of unknown aetiology, only very recently described, that is characterised by a lymphocytic infiltrate with IgG4 producing B cells. We have now established a large cohort of patients and are currently performing detailed assessment of T and B cells profiles to further define pathogenesis (E. Culver Wellcome Trust funded).
|Professor Paul Klenerman||Experimental Medicine Division||University of Oxford||United Kingdom|
|Professor Adrian VS Hill||Jenner Institute||University of Oxford||United Kingdom|
|Dr Alfredo Nicosia||Okairos||Italy|
|Dr Antonella Folgori||Okairos||Italy|
|Dr. Georg Lauer||Gastroenterology||Harvard||United States|
|Dr Harry Dalton||Truro hospital||United Kingdom|
|Professor Theo Rispens||Sanquin||Netherlands|
|Dr Roger Chapman||Experimental Medicine Division||University of Oxford||United Kingdom|
|Prof Stefan Neubauer FMedSci FRCP (RDM)||Cardiovascular Medicine||University of Oxford||United Kingdom|
|Andrea Cox||Johns Hopkins, Baltimore||United States|
|Professor Will Irving||Nottingham University||United Kingdom|
|Dr John McLaughlan||MRC virology Unit, Glasgow||United Kingdom|
|Dr Chris Spencer||Wellcome Trust Centre for Human Genetics||University of Oxford||United Kingdom|
|Professor Chris Holmes||Wellcome Trust Centre for Human Genetics||University of Oxford||United Kingdom|
|Dr Vipul Jairath||TGU||University of Oxford||United Kingdom|
OBJECTIVE: Developing a vaccine that is cross-reactive between HCV genotypes requires data on T cell antigenic targets that extends beyond genotype-1. We characterised T cell immune responses against HCV genotype-3, the most common infecting genotype in the UK and Asia, and assessed within genotype and between genotype cross-reactivity. DESIGN: T cell targets were identified in 140 subjects with either acute, chronic or spontaneously resolved HCV genotype-3 infection using (1) overlapping peptides and (2) putative human leucocyte antigens (HLA)-class-I wild type and variant epitopes through the prior assessment of polymorphic HCV genomic sites associated with host HLA, in IFNγ-ELISpot assays. CD4+/CD8+ T cell subsets were defined and viral variability at T cell targets was determined through population analysis and viral sequencing. T cell cross-reactivity between genotype-1 and genotype-3 variants was assessed. RESULTS: In resolved genotype-3 infection, T cells preferentially targeted non-structural proteins at a high magnitude, whereas in chronic disease T cells were absent or skewed to target structural proteins. Additional responses to wild type but not variant HLA predicted peptides were defined. Major sequence viral variability was observed within genotype-3 and between genotypes 1 and 3 HCV at T cell targets in resolved infection and at dominant epitopes, with limited T cell cross-reactivity between viral variants. Overall 41 CD4/CD8+ genotype-3 T cell targets were identified with minimal overlap with those described for HCV genotype-1. CONCLUSIONS: HCV T cell specificity is distinct between genotypes with limited T cell cross-reactivity in resolved and chronic disease. Therefore, viral regions targeted in natural HCV infection may not serve as attractive targets for a vaccine that aims to protect against multiple HCV genotypes. Hide abstract
A protective vaccine against hepatitis C virus (HCV) remains an unmet clinical need. HCV infects millions of people worldwide and is a leading cause of liver cirrhosis and hepatocellular cancer. Animal challenge experiments, immunogenetics studies, and assessment of host immunity during acute infection highlight the critical role that effective T cell immunity plays in viral control. In this first-in-man study, we have induced antiviral immunity with functional characteristics analogous to those associated with viral control in natural infection, and improved upon a vaccine based on adenoviral vectors alone. We assessed a heterologous prime-boost vaccination strategy based on a replicative defective simian adenoviral vector (ChAd3) and modified vaccinia Ankara (MVA) vector encoding the NS3, NS4, NS5A, and NS5B proteins of HCV genotype 1b. Analysis used single-cell mass cytometry and human leukocyte antigen class I peptide tetramer technology in healthy human volunteers. We show that HCV-specific T cells induced by ChAd3 are optimally boosted with MVA, and generate very high levels of both CD8(+) and CD4(+) HCV-specific T cells targeting multiple HCV antigens. Sustained memory and effector T cell populations are generated, and T cell memory evolved over time with improvement of quality (proliferation and polyfunctionality) after heterologous MVA boost. We have developed an HCV vaccine strategy, with durable, broad, sustained, and balanced T cell responses, characteristic of those associated with viral control, paving the way for the first efficacy studies of a prophylactic HCV vaccine. Hide abstract
Viral diversity is a challenge to the development of a hepatitis C virus (HCV) vaccine. Following vaccination of humans with adenoviral vectors, we determined the capacity of T cells to target common viral variants at immundominant epitopes ex vivo. We identified two major variants for epitopes NS3(1073) and NS3(1446), and multiple variants for epitope NS3(1406) that occurred in >5% of genotype 1 and 3 sequences at a population level. Cross-reactivity of vaccine-induced T cells was determined using variant peptides in IFN-γ ELISPOT assays. Vaccine-induced T cells targeted approximately 90% of NS3(1073) genotype 1 sequences and 50% of NS3(1446) genotype 1 and 3 sequences. For NS3(1406), 62% of subtype-1b sequences were targeted. Next, we assessed whether an in vitro priming system, using dendritic cells and T cells from healthy donors, could identify a variant of NS3(1406) that was maximally cross-reactive. In vitro priming assays showed that of those tested the NS3(1406) vaccine variant was the most immunogenic. T cells primed with genotype 1 variants from subtype 1a or 1b were broadly cross-reactive with other variants from the same subtype. We conclude that immunization with candidate HCV adenoviral vaccines generates cross-reactive T cells at immunodominant epitopes. The degree of cross-reactivity varies between epitopes and may be HCV-subtype specific. Hide abstract
OBJECTIVES: Type I autoimmune pancreatitis (AIP) and IgG4-related sclerosing cholangitis (IgG4-related SC) are now recognized as components of a multisystem IgG4-related disease (IgG4-RD). We aimed to define the clinical course and long-term outcomes in patients with AIP/IgG4-SC recruited from two large UK tertiary referral centers. METHODS: Data were collected from 115 patients identified between 2004 and 2013, and all were followed up prospectively from diagnosis for a median of 33 months (range 1-107), and evaluated for response to therapy, the development of multiorgan involvement, and malignancy. Comparisons were made with national UK statistics. RESULTS: Although there was an initial response to steroids in 97%, relapse occurred in 50% of patients. IgG4-SC was an important predictor of relapse (P<0.01). Malignancy occurred in 11% shortly before or after the diagnosis of IgG4-RD, including three hepatopancreaticobiliary cancers. The risk of any cancer at diagnosis or during follow-up when compared with matched national statistics was increased (odds ratio=2.25, CI=1.12-3.94, P=0.02). Organ dysfunction occurred within the pancreas, liver, kidney, lung, and brain. Mortality occurred in 10% of patients during follow-up. The risk of death was increased compared with matched national statistics (odds ratio=2.07, CI=1.07-3.55, P=0.02). CONCLUSIONS: Our findings suggest that AIP and IgG4-SC are associated with significant morbidity and mortality owing to extrapancreatic organ failure and malignancy. Detailed clinical evaluation for evidence of organ dysfunction and associated malignancy is required both at first presentation and during long-term follow-up. Hide abstract
UNLABELLED: Hepatitis C virus (HCV) exhibits high genetic diversity, characterized by regional variations in genotype prevalence. This poses a challenge to the improved development of vaccines and pan-genotypic treatments, which require the consideration of global trends in HCV genotype prevalence. Here we provide the first comprehensive survey of these trends. To approximate national HCV genotype prevalence, studies published between 1989 and 2013 reporting HCV genotypes are reviewed and combined with overall HCV prevalence estimates from the Global Burden of Disease (GBD) project. We also generate regional and global genotype prevalence estimates, inferring data for countries lacking genotype information. We include 1,217 studies in our analysis, representing 117 countries and 90% of the global population. We calculate that HCV genotype 1 is the most prevalent worldwide, comprising 83.4 million cases (46.2% of all HCV cases), approximately one-third of which are in East Asia. Genotype 3 is the next most prevalent globally (54.3 million, 30.1%); genotypes 2, 4, and 6 are responsible for a total 22.8% of all cases; genotype 5 comprises the remaining <1%. While genotypes 1 and 3 dominate in most countries irrespective of economic status, the largest proportions of genotypes 4 and 5 are in lower-income countries. CONCLUSION: Although genotype 1 is most common worldwide, nongenotype 1 HCV cases—which are less well served by advances in vaccine and drug development—still comprise over half of all HCV cases. Relative genotype proportions are needed to inform healthcare models, which must be geographically tailored to specific countries or regions in order to improve access to new treatments. Genotype surveillance data are needed from many countries to improve estimates of unmet need. Hide abstract
Background & Aims With the increasing prevalence of liver disease worldwide, there is an urgent clinical need for reliable methods to diagnose and stage liver pathology. Liver biopsy, the current gold standard, is invasive and limited by sampling and observer dependent variability. In this study, we aimed to assess the diagnostic accuracy of a novel magnetic resonance protocol for liver tissue characterisation. Methods We conducted a prospective study comparing our magnetic resonance technique against liver biopsy. The individual components of the scanning protocol were T1 mapping, proton spectroscopy and T2â mapping, which quantified liver fibrosis, steatosis and haemosiderosis, respectively. Unselected adult patients referred for liver biopsy as part of their routine care were recruited. Scans performed prior to liver biopsy were analysed by physicians blinded to the histology results. The associations between magnetic resonance and histology variables were assessed. Receiver-operating characteristic analyses were also carried out. Results Paired magnetic resonance and biopsy data were obtained in 79 patients. Magnetic resonance measures correlated strongly with histology (rs = 0.68 p <0.0001 for fibrosis; rs = 0.89 p <0.001 for steatosis; r s = -0.69 p <0.0001 for haemosiderosis). The area under the receiver operating characteristic curve was 0.94, 0.93, and 0.94 for the diagnosis of any degree of fibrosis, steatosis and haemosiderosis respectively. Conclusion The novel scanning method described here provides high diagnostic accuracy for the assessment of liver fibrosis, steatosis and haemosiderosis and could potentially replace liver biopsy for many indications. This is the first demonstration of a non-invasive test to differentiate early stages of fibrosis from normal liver. © 2013 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved. Hide abstract
BACKGROUND & AIMS: With the increasing prevalence of liver disease worldwide, there is an urgent clinical need for reliable methods to diagnose and stage liver pathology. Liver biopsy, the current gold standard, is invasive and limited by sampling and observer dependent variability. In this study, we aimed to assess the diagnostic accuracy of a novel magnetic resonance protocol for liver tissue characterisation. METHODS: We conducted a prospective study comparing our magnetic resonance technique against liver biopsy. The individual components of the scanning protocol were T1 mapping, proton spectroscopy and T2* mapping, which quantified liver fibrosis, steatosis and haemosiderosis, respectively. Unselected adult patients referred for liver biopsy as part of their routine care were recruited. Scans performed prior to liver biopsy were analysed by physicians blinded to the histology results. The associations between magnetic resonance and histology variables were assessed. Receiver-operating characteristic analyses were also carried out. RESULTS: Paired magnetic resonance and biopsy data were obtained in 79 patients. Magnetic resonance measures correlated strongly with histology (r(s)=0.68 p<0.0001 for fibrosis; r(s)=0.89 p<0.001 for steatosis; r(s)=-0.69 p<0.0001 for haemosiderosis). The area under the receiver operating characteristic curve was 0.94, 0.93, and 0.94 for the diagnosis of any degree of fibrosis, steatosis and haemosiderosis respectively. CONCLUSION: The novel scanning method described here provides high diagnostic accuracy for the assessment of liver fibrosis, steatosis and haemosiderosis and could potentially replace liver biopsy for many indications. This is the first demonstration of a non-invasive test to differentiate early stages of fibrosis from normal liver. Hide abstract
To date, very large scale sequencing of many clinically important RNA viruses has been complicated by their high population molecular variation, which creates challenges for polymerase chain reaction and sequencing primer design. Many RNA viruses are also difficult or currently not possible to culture, severely limiting the amount and purity of available starting material. Here, we describe a simple, novel, high-throughput approach to Norovirus and Hepatitis C virus whole genome sequence determination based on RNA shotgun sequencing (also known as RNA-Seq). We demonstrate the effectiveness of this method by sequencing three Norovirus samples from faeces and two Hepatitis C virus samples from blood, on an Illumina MiSeq benchtop sequencer. More than 97% of reference genomes were recovered. Compared with Sanger sequencing, our method had no nucleotide differences in 14,019 nucleotides (nt) for Noroviruses (from a total of 2 Norovirus genomes obtained with Sanger sequencing), and 8 variants in 9,542 nt for Hepatitis C virus (1 variant per 1,193 nt). The three Norovirus samples had 2, 3, and 2 distinct positions called as heterozygous, while the two Hepatitis C virus samples had 117 and 131 positions called as heterozygous. To confirm that our sample and library preparation could be scaled to true high-throughput, we prepared and sequenced an additional 77 Norovirus samples in a single batch on an Illumina HiSeq 2000 sequencer, recovering >90% of the reference genome in all but one sample. No discrepancies were observed across 118,757 nt compared between Sanger and our custom RNA-Seq method in 16 samples. By generating viral genomic sequences that are not biased by primer-specific amplification or enrichment, this method offers the prospect of large-scale, affordable studies of RNA viruses which could be adapted to routine diagnostic laboratory workflows in the near future, with the potential to directly characterize within-host viral diversity. Hide abstract
IL28B host genetic make-up is known to play a critical role in the outcome of genotype 1 hepatitis C virus (HCV) infection in the context of both primary infection and therapy. However, the role of IL28B in subtype 3a infection remains unclear, and has not yet been assessed in the UK population where subtype 3a is dominant. In this study, we evaluated the role of the IL28B single-nucleotide polymorphism rs8099917 in 201 patients recruited from two well-defined cohorts (from Nottingham and Oxford), treated with the standard-of-care therapy of pegylated interferon and ribavirin for 24 weeks. We showed that the 'favourable' IL28B gene was associated with a rapid virological response to therapy at 4 weeks (P<0.0001), but not with a sustained virological response to therapy. The median viral load at baseline, before therapy, was markedly increased in people with the 'favourable' IL28B genotype [median viral load for the TT allele, 925,961 IU ml(-1) (range 2200-21,116,965 IU ml(-1)), and for the GT or GG allele, 260,284 IU ml(-1) (range 740-7,560,000 IU ml(-1)); P = 0.0010]. Our results suggest that the host genetic response plays an important role in early viral clearance of subtype 3a virus from the blood. However, significant reservoirs of infection must persist, as viral relapse is common, even in those with the favourable host genotype. Hide abstract
BACKGROUND: Hepatitis C virus (HCV) genotype-3a infection is now the dominant strain in South Asia and the UK. Characteristic features include a favourable response to therapy; the reasons for this are unknown but may include distinct genotype-3a-specific T cell immunity. In contrast to genotype-1 infection, T cell immunity to this subtype is poorly defined. OBJECTIVES: The aims of the study were to (1) define the frequency, specificity and cross-reactivity of T cell immunity across the whole viral genome in genotype-3a infection and (2) assess the impact of interferon (IFN)-α/ribavirin on T cell immunity. DESIGN: T cell responses in chronic and resolved HCV genotype-3a were analysed in comparison with genotype-1 infection (total n=85) using specific peptide panels in IFN-γ ELISpot assays. T cell responses were followed longitudinally in a subset of genotype-3a infected patients receiving therapy. Responses were further defined by CD4 and CD8 subset analysis, sequencing of autologous virus and cross-reactivity of genotype-3a with genotype-1a/-1b antigens. RESULTS: CD8 T cell responses commonly targeted the non-structural (NS) proteins in chronic genotype-3a infection whereas in genotype-1 infection CD4 responses targeting HCV core predominated (p=0.0183). Resolved infection was associated with CD4 T cells targeting NS proteins. Paradoxically, a sustained response to therapy was associated with a brisk decline in virus-specific and total lymphocyte counts that recovered after treatment. CONCLUSION: HCV genotype-3a exhibits a distinct T cell specificity with implications for vaccine design. However, our data do not support the theory that genotype-3a viral clearance with therapy is associated with an enhanced antiviral T cell response. Paradoxically, a reduction in these responses may serve as a biomarker of IFN responsiveness. Hide abstract
Replication-defective adenovirus vectors based on human serotype 5 (Ad5) induce protective immune responses against diverse pathogens and cancer in animal models, as well as elicit robust and sustained cellular immunity in humans. However, most humans have neutralizing antibodies to Ad5, which can impair the immunological potency of such vaccines. Here, we show that rare serotypes of human adenoviruses, which should not be neutralized in most humans, are far less potent as vaccine vectors than Ad5 in mice and nonhuman primates, casting doubt on their potential efficacy in humans. To identify novel vaccine carriers suitable for vaccine delivery in humans, we isolated and sequenced more than 1000 adenovirus strains from chimpanzees (ChAd). Replication-defective vectors were generated from a subset of these ChAd serotypes and screened to determine whether they were neutralized by human sera and able to grow in human cell lines. We then ranked these ChAd vectors by immunological potency and found up to a thousandfold variation in potency for CD8+ T cell induction in mice. These ChAd vectors were safe and immunologically potent in phase 1 clinical trials, thereby validating our screening approach. These data suggest that the ChAd vectors developed here represent a large collection of non-cross-reactive, potent vectors that may be exploited for the development of new vaccines. Hide abstract
Currently, no vaccine exists for hepatitis C virus (HCV), a major pathogen thought to infect 170 million people globally. Many studies suggest that host T cell responses are critical for spontaneous resolution of disease, and preclinical studies have indicated a requirement for T cells in protection against challenge. We aimed to elicit HCV-specific T cells with the potential for protection using a recombinant adenoviral vector strategy in a phase 1 study of healthy human volunteers. Two adenoviral vectors expressing NS proteins from HCV genotype 1B were constructed based on rare serotypes [human adenovirus 6 (Ad6) and chimpanzee adenovirus 3 (ChAd3)]. Both vectors primed T cell responses against HCV proteins; these T cell responses targeted multiple proteins and were capable of recognizing heterologous strains (genotypes 1A and 3A). HCV-specific T cells consisted of both CD4+ and CD8+ T cell subsets; secreted interleukin-2, interferon-γ, and tumor necrosis factor-α; and could be sustained for at least a year after boosting with the heterologous adenoviral vector. Studies using major histocompatibility complex peptide tetramers revealed long-lived central and effector memory pools that retained polyfunctionality and proliferative capacity. These data indicate that an adenoviral vector strategy can induce sustained T cell responses of a magnitude and quality associated with protective immunity and open the way for studies of prophylactic and therapeutic vaccines for HCV. Hide abstract
JOURNAL OF THROMBOSIS AND HAEMOSTASIS, 9 pp. 50-50.2011. Rotational thromboelastometry in cirrhosis: hypercoagulable and hyperfibrinolytic
Hepatitis C virus (HCV) infects more than 170 million people globally and is a leading cause of liver cirrhosis, transplantation and hepatocellular carcinoma. Current gold-standard therapy often fails, has significant side effects in many cases and is expensive. No vaccine is currently available. The fact that a significant proportion of infected people spontaneously control HCV infection in the setting of an appropriate immune response suggests that a vaccine for HCV is a realistic goal. A comparative analysis of infected people with distinct clinical outcomes has enabled the characterization of many important innate and adaptive immune processes associated with viral control. It is clear that a successful HCV vaccine will need to exploit and enhance these natural immune defense mechanisms. New HCV vaccine approaches, including peptide, recombinant protein, DNA and vector-based vaccines, have recently reached Phase I/II human clinical trials. Some of these technologies have generated robust antiviral immunity in healthy volunteers and infected patients. The challenge now is to move forward into larger at-risk or infected populations to truly test efficacy. Hide abstract
For two decades the scientific community has sought to understand why some people clear hepatitis C virus (HCV) and others do not. Recently, several large genome-wide association studies have identified single nucleotide polymorphisms (SNPs) linked to interferon lambda 3 (IFNλ3) that are associated with the spontaneous resolution and successful treatment of HCV infection. These observations are generating intense research activity; the hope is that IFNλ3 genetic variants may serve as important predictive biomarkers of treatment outcome and offer new insights into the biological pathways involved in viral control. A pharmacogenomic treatment approach for HCV can now be envisaged, with the incorporation of host genetic variants into a predictive treatment algorithm with other factors. The SNPs associated with the clinical outcome of HCV infection are located some distance from the IFNλ3 gene itself, and causal genetic variants have yet to be clearly defined. Locating these causal variants, mapping in detail the IFNλ3 signalling pathways and determining the downstream genetic signature so induced will clarify the role of IFNλ3 in the pathogenesis of HCV. Clinical studies assessing safety and efficacy in the treatment of HCV with exogenous IFNλ3 are currently underway. Early results suggest that IFNλ3 treatment inhibits HCV replication and is associated with a limited side effect profile. However, hepatotoxicity in both healthy volunteers and HCV-infected patients has been described. This review discusses the genetic studies that link IFNλ3 to both the spontaneous resolution and treatment-induced clearance of HCV and the potential impact of this in clinical practice, the biology of IFNλ3 as currently understood and how this may impact on HCV infection, and describes the early studies that assess the role of this cytokine in the treatment of patients with HCV. Hide abstract
A xenotropic murine leukemia virus-related virus (XMRV) has recently been reported in association with prostate cancer and chronic fatigue syndrome, with a prevalence of up to 3.7% in the healthy population. We looked for XMRV in 230 patients with human immunodeficiency virus type 1 or hepatitis C infection. XMRV was undetectable in plasma or peripheral blood mononuclear cells by polymerase chain reaction targeting XMRV gag or env. T cell responses to XMRV Gag were undetectable in peripheral blood mononuclear cells by ex vivo gamma interferon enzyme-linked immunospot assay. In our cohorts, XMRV was not enriched in patients with blood-borne or sexually transmitted infections from the United Kingdom and Western Europe. Hide abstract
JOURNAL OF VIROLOGY, 84 (3), pp. 1664-1664. | Read more2010. Full-Length Characterization of Hepatitis C Virus Subtype 3a Reveals Novel Hypervariable Regions under Positive Selection during Acute Infection (vol 83, pg 11456, 2009)
BACKGROUND: The effect that high-dose interferon (IFN)-alpha induction therapy for hepatitis C virus (HCV) infection has on cellular immune responses is currently unknown. METHODS: Thirty-one treatment-naive patients with chronic HCV infection received amantadine and ribavirin, combined with 6 weeks of high-dose IFN-alpha-2b induction therapy followed by weekly pegylated IFN-alpha-2b, for 24 or 48 weeks. Using IFN-gamma and interleukin (IL)-2 enzyme-linked immunospot (ELISpot) assays, we analyzed the pattern of cytokine secretion by structural and nonstructural HCV- and cytomegalovirus (CMV)-specific T cells before, during, and after therapy. RESULTS: HCV-specific T cell responses, which were predominantly IFN-gamma secreting and which correlated with alanine transaminase levels (r2 = 0.45; P = .001), were found before treatment in 10 of 15 patients with a sustained virological response (SVR) and in 11 of 16 in the non-SVR group. There was a striking loss of IFN-gamma and IL-2 HCV-specific T cells during therapy, predominantly in the SVR group. This response recovered after cessation of therapy, regardless of outcome. Suppression of CMV-specific T cell responses, in addition to total lymphocyte counts, was also observed. CONCLUSIONS: High-dose IFN-alpha induction therapy leads to a profound decline in IL-2- and IFN-gamma-secreting HCV- and CMV-specific T cells. These data indicate that restoration of T cell responses is unlikely to be causally linked to an early response or SVR to therapy. Hide abstract
Studies assessing the function of monocyte derived dendritic cells (MD-DC) in individuals with hepatitis C virus (HCV) infection have shown conflicting results. Impaired MD-DC function in chronic HCV infection would have important implications both for understanding the pathogenesis of HCV infection and in the use of autologous MD-DC in vaccination strategies. We determined the allostimulatory capacity of MD-DC in the same patient before and after HCV infection. Next, the phenotype, cytokine production and allostimulatory function of immature and mature MD-DC in individuals with persistent HCV infection were compared directly with MD-DC from healthy individuals. Finally, we assessed the ability of MD-DC to prime autologous naïve peptide specific CD8+ T cells using HLA-A2 class-I tetramers. DCs retained the same allostimulatory capacity before and following the establishment of persistent HCV infection. The surface phenotype and the amount of interleukin (IL)-10 and IL-12(p70) produced during DC maturation did not differ between HCV-infected individuals and healthy controls. Mature DCs from HCV-infected individuals performed comparably in an allogeneic MLR compared with healthy individuals. Mature MD-DC from HCV-infected individuals stimulated the expansion of peptide specific naïve CD8+ T cells. MD-DC from HCV-infected and healthy individuals are phenotypically indistinguishable and perform comparably in functional assays. Hide abstract
Alpha interferon and ribavirin are required in combination to achieve a sustained virological response in the treatment of hepatitis C virus (HCV) infection. Alpha interferon has direct antiviral activity and also enhances HCV-specific T-cell responses. Ribavirin has little direct activity against HCV but reduces hepatic inflammation. It is therefore likely that these drugs in combination have hitherto unidentified immunological effects. In the present study we investigated the effects of alpha interferon and ribavirin on dendritic cell (DC) maturation and cytokine production induced by double-stranded RNA in vitro. Alpha interferon alone enhanced the expression of HLA class I, HLA class II, and CD86 on immature DCs but did not stimulate full DC maturation, which requires the expression of CD83. Alpha interferon enhanced the production of interleukin 12 p70 [IL-12(p70)] and tumor necrosis factor alpha (TNF-alpha) but had no effect on IL-10 production. In contrast, ribavirin at physiological doses had no effect on DC maturation but markedly suppressed the production of TNF-alpha, IL-10, and IL-12(p70). The suppression of cytokines by ribavirin cannot be explained by the induction of DC apoptosis or cell death. Quantitative PCR confirmed that cytokine suppression occurs at the level of mRNA. The suppression of IL-12(p70) and TNF-alpha in maturing DCs may explain the reduction in hepatic inflammation observed during ribavirin monotherapy. Combination alpha interferon-ribavirin therapy may alter the cytokine profile of maturing DCs overall by suppressing IL-10 production but maintaining IL-12(p70) and TNF-alpha production, a pattern that would favor viral elimination through downstream effects on T cells. Hide abstract
A major breakthrough in cellular immunology has been the development of HLA class I tetramers to analyze CD8(+) T cell responses. However, in many situations, including persistent virus infection, specific T cell responses are rarely detected using this technology. This raises the question of whether such responses are 'deleted' (or 'exhausted') or present below the conventional detection limit for class I tetramer staining. In particular, persistent hepatitis C virus (HCV) infection is characterized by very weak or apparently absent specific CD8(+) T cell responses, even though they are readily detectable in acute disease. Therefore, we assessed the use of anti-PE-labeled magnetic beads to enrich tetramer-positive HCV-specific T cells and identify previously undetectable populations. Using the enrichment technique, HCV-specific T cells could be detected in the majority of infected individuals, whereas these responses were not detected using conventional tetramer staining (8/15 vs. 1/15; p=0.01). Magnetic enrichment could reliably detect very rare HCV-specific responses at frequencies of >0.0011% of CD8(+) T cells (approximately 1/million PBMC), and phenotypic analysis of these rare populations was possible. Therefore, this direct ex vivo technique revealed the persistence of very low frequencies of virus-specific CD8(+) T cells during chronic virus infection and is readily transferable to the study of other viral, self- or tumor-specific T cells. Hide abstract
Hepatitis C virus (HCV) readily sets up a persistent infection and is a major cause of liver disease worldwide. Interferon alfa and ribavirin therapy lead to sustained clearance of virus in 31% to 64% of patients with type 1 and non-type 1 genotypes, respectively. It is not clear to what extent these drugs act directly to reduce HCV replication, or indirectly via host immune responses, and what evoked immune responses are associated with clinical outcome. We have examined prospectively 15 patients with chronic HCV infection before, during, and after combination therapy. Quantitative assays for HCV antigen-specific CD4+ and CD8+ T-cell responses, and flow cytometric assays for analysis of the phenotype of T cells, in addition to viral sequencing of core protein, were performed throughout the treatment and follow-up period over 18 months. We found enhancement of proliferative T-cell responses during therapy. Proliferative responses are strikingly heterogeneous in terms of specificity, kinetics, and magnitude. Proliferative responses are often not associated with interferon-gamma release. T-cell responses are rarely sustained irrespective of treatment outcome and this is not due to the evolution of new immune escape variants. T-cell responses tend to peak late in the course of treatment. In conclusion, combination therapy for HCV has a transient effect on host virus-specific T cells in the blood. Induction of sustained T-cell responses may require additional immune modulation later in therapy. Hide abstract
Defining the immune control of Hepatitis B virus (HBV) infection through HBV genomic and T cell mapping technologies; implications for immunotherapy.
HBV infects millions of people globally and is the leading cause of liver cirrhosis and hepatocellular cancer. Drug therapies are available to suppress viral replication, but in most cases therapy must be continued indefinitely. This means they are not used in resource poor setting where the burden of disease is highest.Over recent years our laboratory has built up considerable expertise in the fine mapping and functional analysis of T cell immune responses to pathogens, and in the generation o ...
An exploration of the characteristics of vaccine-induced T cell responses to novel HIV-1 and HCV vaccines and their contribution to protective immunity
HIV-1 and hepatitis C virus (HCV) are major global pathogens with high rates of morbidity and mortality. Co-infection is common, due to overlapping transmission risks. PEACHI (Prevention of hepatitis C and HIV co-infections) is an Oxford-led EU FP7-funded project that aims to develop effective viral vectored vaccines for prevention of HIV-1, HCV and co-infection. The vaccines exploit potent replication-defective viral vectors (simian adenovirus, ChAd and modified vaccinia virus Ankara, MVA) and ...
Characterisation and manipulation of novel pathways that regulate gene expression to enhance the efficacy of vectored DNA vaccines
Replication of RNA and small DNA viruses in mammalian cells requires a genome that both codes for replication and structural proteins necessary to replicate their genomes and package them into virions. They additionally need to evade sophisticated and powerful interferon-coupled cellular defences and inflammatory and adaptive immune responses in the host. Viruses have developed a series of counter-measures to prevent induction of interferon (IFN)-β on infection of cells and disrupt systemic resp ...