Dr Lucy Dorrell
|Technology Exchange:||Cell sorting, Cellular immunology, Flow cytometry and Vaccine production and evaluation|
|Scientific Themes:||Immunology & Infectious Disease|
|Keywords:||hiv, t cell, vaccine, clinical trial, viral vector and antiretroviral|
Currently, an estimated 33 million people are living with HIV-1 infection. Despite progress in expanding access to antiretroviral therapy (ART), 9 million who need immediate treatment are not receiving it. The overall aim of this research programme is to develop immunotherapy for HIV-1 infection which will reduce dependence on ART. Since virus-specific CD8+ T cell responses are a key determinant of the rate at which people with HIV-1 infection progress to AIDS, we are investigating whether these responses can be amplifed and / or re-targeted towards conserved viral epitopes by vaccination during HAART. The goal is to limit viral escape and enhance immune control of HIV-1 replication. We have previously shown that vaccination of chronically infected patients with DNA- and modified vaccinia virus Ankara (MVA)-vectored vaccines expressing an HIV-1 immunogen developed by Dr Tomáš Hanke (HIU), boosts HIV-specific T cell responses. We are now testing new HIV-1 immunogens and new viral vectors for the delivery of these immunogens in healthy volunteers and in HIV-1-infected patients. We aim to address questions which are critical to the development of effective therapeutic and prevention strategies:
- (i) is targeting of highly conserved viral epitopes by CD8+ T cells essential for immune control
- (ii) how do qualitative aspects of these responses such as breadth, viral inhibitory capacity, tissue-homing characteristics influence outcome? (see Yang H, Dorrell L et al. J Infect Dis 2012, Epub)
- (iii) can we combine an effective vaccination strategy with antiretroviral therapy and other drugs targeted latently infected cells to achieve a functional cure for patients?
|Prof Tomas Hanke||Jenner Institute||Oxford University||UK|
|Prof Miles Davenport||University of New South Wales||Australia|
|Dr Brian J Angus||Tropical Medicine||Oxford University||UK|
|Dr Cameron Holloway||University of Oxford||UK|
|Prof Stefan Neubauer||Oxford University||UK|
|Dr Christian Brander||Fundacio irsiCaixa||Spain|
|Prof David Goldstein||Center for HIV/AIDS Vaccine Immunology (CHAVI), Duke University||USA|
|Dr Persephone Borrow||Experimental Medicine Division||Oxford University||UK|
|Dr Rebecca Ashfield||Immunocore Ltd||UK|
The capacity of CD8+ T cells to inhibit HIV-1 replication in vitro strongly correlates with virus control in vivo. Post-hoc evaluations of HIV-1 vaccine candidates suggest that this immunological parameter is a promising benchmark of vaccine efficacy. Large-scale analysis of CD8+ T cell antiviral activity requires a rapid, robust and economical assay for accurate quantification of HIV-1 infection in primary CD4+ T cells. Detection of intracellular HIV-1 p24 antigen (p24 Ag) by flow cytometry is one such method but it is thought to be less sensitive and quantitative than p24 Ag ELISA. We report that fixation and permeabilisation of HIV-infected cells using paraformaldehyde/50% methanol/Nonidet P-40 instead of a conventional paraformaldehyde/saponin-based protocol improved their detection across multiplicities of infection (MOI) ranging from 10(-2) to 8×10(-5), and by nearly two-fold (p<0.001) at the optimal MOI tested (10(-2)). The frequency of infected cells was strongly correlated with p24 Ag release during culture, thus validating its use as a measure of productive infection. We were also able to quantify infection with a panel of HIV-1 isolates representing the major clades. The protocol described here is rapid and cost-effective compared with ELISA and thus could be a useful component of immune monitoring of HIV-1 vaccines and interventions to reduce viral reservoirs. Hide abstract
Human Molecular Genetics, 22 (9), pp. 1903-1910.2013. A genome-wide association study of resistance to HIV infection in highly exposed uninfected individuals with hemophilia A
JOURNAL OF INFECTIOUS DISEASES, 206 (4), pp. 552-561. | Read more2012. Antiviral Inhibitory Capacity of CD8+ T cells Predicts the Rate of CD4+ T-Cell Decline in HIV-1 Infection
We investigated whether vaccination of healthy HIV-seronegative and HIV-1-seropositive antiretroviral therapy-treated subjects with recombinant modified vaccinia virus Ankara expressing an HIV-1 immunogen (MVA.HIVA) induced MVA-specific T cell responses. Using IFN-γ Elispot assays, we observed new or increased responses to MVA virus in 52% of HIV-seronegative subjects and 93% HIV-1 seropositive subjects; MVA-specific T cell frequencies were generally low and correlated poorly with T cell responses to the HIV-1 immunogen. In two vaccinees, responses were mapped to CD8+ T cell epitopes present in replication-competent vaccinia virus. These data support further evaluation of MVA as a viral vector for HIV-1 immunogens. Hide abstract
SCIENCE, 324 (5932), pp. 1264-1265.2009. A Step Ahead on the HIV Collaboratory
J Immunol, 179 (1), pp. 597-606. Read abstract2007. Broad TCR usage in functional HIV-1-specific CD8+ T cell expansions driven by vaccination during highly active antiretroviral therapy.
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. Hide abstract
One of the big roadblocks in development of HIV-1/AIDS vaccines is the enormous diversity of HIV-1, which could limit the value of any HIV-1 vaccine candidate currently under test. Hide abstract
Virus-specific CD4+ T cells with IL-2-secreting and/or proliferative capacity are detected readily in HIV-1-infected long-term nonprogressors and rarely in persons with untreated progressive infection. The contribution of these cells to viraemia control is uncertain, but this question might be addressed in clinical therapeutic vaccination studies. However, the quality of T helper responses induced by currently available HIV-1 vaccine candidates has not been explored in depth. We determined the effect of vaccination with modified vaccinia virus Ankara (MVA) expressing HIV-1 gag p24/p17 (MVA.HIVA) on HIV-1-specific CD4+ T cell responses in 16 chronically infected, highly active antiretroviral therapy (HAART)-treated subjects using CD8-depleted IFN-gamma ELISPOT assays, intracellular cytokine staining assays for IL-2 and IFN-gamma, and a CFSE-based proliferation assay. Gag-specific CD4+ T cell responses were significantly increased in magnitude and breadth after vaccination and targeted both known and new epitopes, several of which were also recognised by healthy HIV-uninfected volunteers immunised with the same vaccines. The frequencies of CD4+ T cells expressing IL-2 or IFN-gamma, alone or simultaneously, were also augmented. These findings indicate that functional virus-specific T helper cells can be boosted by vaccination in chronic HIV-1 infection. Further evaluation of their role in viraemia control is warranted. Hide abstract
Affordable therapeutic strategies that induce sustained control of human immunodeficiency virus type 1 (HIV-1) replication and are tailored to the developing world are urgently needed. Since CD8(+) and CD4(+) T cells are crucial to HIV-1 control, stimulation of potent cellular responses by therapeutic vaccination might be exploited to reduce antiretroviral drug exposure. However, therapeutic vaccines tested to date have shown modest immunogenicity. In this study, we performed a comprehensive analysis of the changes in virus-specific CD8(+) and CD4(+) T-cell responses occurring after vaccination of 16 HIV-1-infected individuals with a recombinant modified vaccinia virus Ankara-vectored vaccine expressing the consensus HIV-1 clade A Gag p24/p17 sequences and multiple CD8(+) T-cell epitopes during highly active antiretroviral therapy. We observed significant amplification and broadening of CD8(+) and CD4(+) gamma interferon responses to vaccine-derived epitopes in the vaccinees, without rebound viremia, but not in two unvaccinated controls followed simultaneously. Vaccine-driven CD8(+) T-cell expansions were also detected by tetramer reactivity, predominantly in the CD45RA(-) CCR7(+) or CD45RA(-) CCR7(-) compartments, and persisted for at least 1 year. Expansion was associated with a marked but transient up-regulation of CD38 and perforin within days of vaccination. Gag-specific CD8(+) and CD4(+) T-cell proliferation also increased postvaccination. These data suggest that immunization with MVA.HIVA is a feasible strategy to enhance potentially protective T-cell responses in individuals with chronic HIV-1 infection. Hide abstract
To determine whether long-term HAART in chronic HIV-1 infection restores fully functional Mycobacterium tuberculosis (MTB)-specific CD4 T-cell responses. Hide abstract
AIDS, 25 (1), pp. 27-36.Comprehensive analysis of virus-specific T-cells provides clues for the failure of therapeutic immunization with ALVAC-HIV vaccine.
T cell immune correlates of HIV-1 control and their application to disease prevention and cure strategies
HIV-1 infection can be effectively controlled with combination antiretroviral therapy (ART); however, the global burden of disease continues to outstrip efforts to roll out treatment. Currently available ART does not eradicate the reservoir of latently infected CD4+ cells nor restore effective immunity against HIV-1, therefore, treatment has to be continued for the patient’s lifetime. Recently, the concept of ‘functional cure’ has gained interest following the apparent cure of a single ...