Virological, Immune and Host genetics Markers in the Control of HIV Infection

HIV infection, if left untreated, leads in most cases to the development of wide immune deterioration, opportunistic infections and eventually AIDS and death. The identification of individuals who despite persisting infection show no or few signs of HIV disease progression has spurred hopes that an effective HIV vaccine could be attainable. The design of such a vaccine will greatly depend on the precise definition of disease markers, host genetic and immune characteristics that mediate relative in vivo control of this virus. Accordingly, a number of viral factors and host genetic characteristics have been shown to play a crucial role in the control of HIV disease by delaying progression to AIDS or even preventing infection. There is also an improved understanding of humoral and cellular immune responses in terms of specificity, functional repertoire, longevity and tissue distribution and their ability to contain HIV replication. However, the definition of good immune correlates unequivocally and causally associated with protection or disease progression remains elusive. Here we review work on viral factors, host genetic markers and immunological determinants that have been identified in individuals with superior control of HIV infection or in subjects who remain uninfected despite frequent exposure to the viral pathogen

Novel Approaches Towards a Functional Cure of HIV/AIDS

Altres ajuts: The present work was funded in parts by NIH Grant P01-AI131568Therapeutic approaches towards a functional cure or eradication of HIV have gained renewed momentum upon encouraging data emerging from studies in SIV monkey models and recent results from human clinical studies. However, a multitude of questions remain to be addressed, including how to deal with the latent viral reservoir, how to boost the host immune response to the virus and what the hurdles are to reach relevant viral compartments in the body. Advances have been made especially with regard to identifying agents that can reactivate the latent virus in vivo and boost the cellular and humoral immunity, but it remains largely unclear whether any of these strategies can awaken a sufficiently large fraction of the viral reservoir and whether the boosted immunity can prevent rapid viral replication once antiretroviral treatments are stopped

Definition of the Viral Targets of Protective HIV-1-Specific T Cell Responses

Background: The efficacy of the CTL component of a future HIV-1 vaccine will depend on the induction ofresponses with the most potent antiviral activity and broad HLA class I restriction. However, current HIV vaccinedesigns are largely based on viral sequence alignments only, not incorporating experimental data on T cellfunction and specificity. Methods: Here, 950 untreated HIV-1 clade B or -C infected individuals were tested for responses to sets of 410overlapping peptides (OLP) spanning the entire HIV-1 proteome. For each OLP, a “protective ratio” (PR) wascalculated as the ratio of median viral loads (VL) between OLP non-responders and responders. Results: For both clades, there was a negative relationship between the PR and the entropy of the OLP sequence.There was also a significant additive effect of multiple responses to beneficial OLP. Responses to beneficial OLPwere of significantly higher functional avidity than responses to non-beneficial OLP. They also had superior in-vitroantiviral activities and, importantly, were at least as predictive of individuals’ viral loads than their HLA class Igenotypes. Conclusions: The data thus identify immunogen sequence candidates for HIV and provide an approach for T cellimmunogen design applicable to other viral infections

Molecular Characterization of Heterologous HIV-1gp120 Gene Expression Disruption in Mycobacterium bovis BCG Host Strain: A Critical Issue for Engineering Mycobacterial Based-Vaccine Vectors

Mycobacterium bovis Bacillus Calmette-Guérin (BCG) as a live vector of recombinant bacterial vaccine is a promising system to be used. In this study, we evaluate the disrupted expression of heterologous HIV-1gp120 gene in BCG Pasteur host strain using replicative vectors pMV261 and pJH222. pJH222 carries a lysine complementing gene in BCG lysine auxotrophs. The HIV-1 gp120 gene expression was regulated by BCG hsp60 promoter (in plasmid pMV261) and Mycobacteria spp. α-antigen promoter (in plasmid pJH222). Among 14 rBCG:HIV-1gp120 (pMV261) colonies screened, 12 showed a partial deletion and two showed a complete deletion. However, deletion was not observed in all 10 rBCG:HIV-1gp120 (pJH222) colonies screened. In this study, we demonstrated that E. coli/Mycobacterial expression vectors bearing a weak promoter and lysine complementing gene in a recombinant lysine auxotroph of BCG could prevent genetic rearrangements and disruption of HIV 1gp120 gene expression, a key issue for engineering Mycobacterial based vaccine vectors

HIVconsv vaccines and romidepsin in early-treated HIV-1-infected individuals: safety, immunogenicity and effect on the viral reservoir (Study BCN02)

Kick&kill strategies combining drugs aiming to reactivate the viral reservoir with therapeutic vaccines to induce effective cytotoxic immune responses hold potential to achieve a functional cure for HIV-1 infection. Here, we report on an open-label, single-arm, phase I clinical trial, enrolling 15 early-treated HIV-1-infected individuals, testing the combination of the histone deacetylase inhibitor romidepsin as a latency-reversing agent and the MVA.HIVconsv vaccine. Romidepsin treatment resulted in increased histone acetylation, cell-associated HIV-1 RNA, and T-cell activation, which were associated with a marginally significant reduction of the viral reservoir. Vaccinations boosted robust and broad HIVconsv-specific T cells, which were strongly refocused toward conserved regions of the HIV-1 proteome. During a monitored ART interruption phase using plasma viral load over 2,000 copies/ml as a criterium for ART resumption, 23% of individuals showed sustained suppression of viremia up to 32 weeks without evidence for reseeding the viral reservoir. Results from this pilot study show that the combined kick&kill intervention was safe and suggest a role for this strategy in achieving an immune-driven durable viremic control.Peer ReviewedPostprint (published version

Disruption of the HLA-E/NKG2X axis is associated with uncontrolled HIV infections

The contribution of the HLA-E/NKG2X axis in NK-mediated control of HIV infection remains unclear. We have studied the relationship between HLA-E expression and phenotypical as well as functional characteristics of NK cells, in the context of chronic HIV infection and in an in vitro model of acute infection. High viremia in HIV+ individuals was related to increased HLA-E expression, and changes in NK subpopulations, especially a reduction of the CD56 bright as well as an increase in adaptive NK subpopulation. Uncontrolled HIV infection was also characterized by a reversion of the NKG2A/NKG2C expression ratio and a loss of positive and negative regulation of NK mediated by HLA-E. This was reflected in a lower cytotoxic, degranulation and cytokine production capacity, especially in CD56 bright and adaptive NK. In line with these results, HLA-E expression showed a positive correlation with viral growth inhibition in an in vitro model of acute infection at day 7, which was lost after 14 days of culture. Using HLA-E expressing K562 cells, we determined that only one out of 11 described HIV-derived HLA-E epitopes increased HLA-E surface stability. In spite of that, eight of the 11 epitopes were capable of increasing degranulation and three drove differences in NK-cell mediated cell lysis or cytokine secretion. In conclusion, our results indicate that HLA-E molecules presenting HIV-derived epitopes may sensitize target cells for NK lysis in early HIV infection. However, prolonged exposure to elevated HLA-E expression levels in vivo may lead to NK cell dysfunction and reduced viral control In chronic infection

In vivo effects of romidepsin on T-Cell activation, apoptosis and function in the BCN02 HIV-1 kick&Kill clinical trial

Romidepsin (RMD) is a well-characterized histone deacetylase inhibitor approved for the treatment of cutaneous T-cell lymphoma. in vitro and in vivo studies have demonstrated that it is able to induce HIV-1 gene expression in latently infected CD4+ T cells from HIV-1+ individuals on suppressive antiretroviral therapy. However, in vitro experiments suggested that RMD could also impair T-cell functionality, particularly of activated T cells. Thus, the usefulness of RMD in HIV-1 kick&kill strategies, that aim to enhance the immune system elimination of infected cells after inducing HIV-1 viral reactivation, may be limited. In order to address whether the in vitro observations are replicated in vivo, we determined the effects of RMD on the total and HIV-1-specific T-cell populations in longitudinal samples from the BCN02 kick&kill clinical trial (NCT02616874). BCN02 was a proof-of-concept study in 15 early treated HIV-1+ individuals that combined MVA.HIVconsv vaccination with three weekly infusions of RMD given as a latency reversing agent. Our results show that RMD induced a transient increase in the frequency of apoptotic T cells and an enhanced activation of vaccine-induced T cells. Although RMD reduced the number of vaccine-elicited T cells secreting multiple cytokines, viral suppressive capacity of CD8+ T cells was preserved over the RMD treatment. These observations have important implications for the design of effective kick&kill strategies for the HIV-1 cure

Use of RT-defective HIV virions: new tool to evaluate specific response in chronic asymptomatic HIV-infected individuals

Background Generation of new reagents that can be used to screen or monitor HIV-1-specific responses constituted an interesting field in the development of HIV vaccines to improve their efficacy. Methods We have evaluated the specific T cell response against different types of NL4-3 virions (including NL4-3 aldrithiol-2 treated, NL4-3/ΔRT and R5 envelopes: NL4-3/ΔRT/ΔEnv[AC10] and NL4-3/ΔRT/ΔEnv[Bal]) and against pools of overlapping peptides (15 mer) encompassing the HIV-1 Gag and Nef regions. Cryopreserved PBMC from a subset of 69 chronic asymptomatic HIV positive individuals have been employed using different techniques including IFN-γ ELISPOT assay, surface activation markers and intracellular cytokine staining (ICS) by flow cytometry. Results The differential response obtained against NL4-3 aldrithiol-2 treated and NL4-3/ΔRT virions (25% vs 55%, respectively) allow us to divide the population in three groups: "full-responders" (positive response against both viral particles), "partial-responders" (positive response only against NL4-3/ΔRT virions) and "non-responders" (negative responses). There was no difference between X4 and R5 envelopes. The magnitude of the total responses was higher against NL4-3/ΔRT and was positively correlated with gender and inverse correlated with viral load. On the contrary CD4+ T cell count was not associated with this response. In any case responses to the viruses tended to be lower in magnitude than those detected by the overlapping peptides tested. Finally we have found an increased frequency of HLA-B27 allele (23% vs 9%) and a significant reduction in some activation markers (CD69 and CD38) on T cells surface in responders vs non-responders individuals. Conclusions In summary these virions could be considered as alternative and useful reagents for screening HIV-1-specific T cell responses in HIV exposed uninfected people, HIV infected patients and to assess immunogenicity of new prototypes both in vitro and in vaccine trials, by a feasible, simply, effective and low cost assay

The Genome-wide Methylation Profile of CD4+ T Cells From Individuals With Human Immunodeficiency Virus (HIV) Identifies Distinct Patterns Associated With Disease Progression

Background: Human genetic variation-mostly in the HLA and CCR5 regions-explains 25% of the variability in progression of HIV infection. However, it is also known that viral infections can modify cellular DNA methylation patterns. Therefore, changes in the methylation of CpG islands might modulate progression of HIV infection. Methods: 85 samples were analyzed: 21 elite controllers (EC), 21 HIV-infected subjects before combination antiretroviral therapy (cART) (viremic, 93,325 HIV-1 RNA copies/ml) and under suppressive cART (cART, median of 17 months, <50 HIV-1 RNA copies/ml), and 22 HIV-negative donors (HIVneg). We analyzed the methylation pattern of 485,577 CpG in DNA from peripheral CD4+ T lymphocytes. We selected the most differentially methylated gene (TNF) and analyzed its specific methylation, mRNA expression, and plasma protein levels in 5 individuals before and after initiation of cART. Results: We observed 129 methylated CpG sites (associated with 43 gene promoters) for which statistically significant differences were recorded in viremic vs HIVneg, 162 CpG sites (55 gene promoters) in viremic vs cART, 441 CpG sites (163 gene promoters) in viremic vs EC, but none in EC vs HIVneg. The TNF promoter region was hypermethylated in viremic vs HIVneg, cART, and EC. Moreover, we observed greater plasma levels of TNF in viremic individuals than in EC, cART, and HIVneg. Conclusions: Our study shows that genome methylation patterns vary depending on HIV infection status and progression profile and that these variations might have an impact on controlling HIV infection in the absence of cART

Identification of effective subdominant anti-HIV-1 CD8+ T cells within entire post-infection and post-vaccination immune responses

Ajuts: R01/R56 NIH Grant AI-52779 (GDT), NIH F31 Fellowship (1F31AI106519-01)(TLP), Center for AIDS Research (P30 AI 64518) i Center for HIV/AIDS Vaccine Immunology and Immunogen Discovery, grant number UM1-AI100645-01 (AM)Abstract.Defining the components of an HIV immunogen that could induce effective CD8+ T cell responses is critical to vaccine development. We addressed this question by investigating the viral targets of CD8+ T cells that potently inhibit HIV replication in vitro, as this is highly predictive of virus control in vivo. We observed broad and potent ex vivo CD8+ T cell-mediated viral inhibitory activity against a panel of HIV isolates among viremic controllers (VC, viral loads <5000 copies/ml), in contrast to unselected HIV-infected HIV Vaccine trials Network (HVTN) participants. Viral inhibition of clade-matched HIV isolates was strongly correlated with the frequency of CD8+ T cells targeting vulnerable regions within Gag, Pol, Nef and Vif that had been identified in an independent study of nearly 1000 chronically infected individuals. These vulnerable and so-called "beneficial" regions were of low entropy overall, yet several were not predicted by stringent conservation algorithms. Consistent with this, stronger inhibition of clade-matched than mismatched viruses was observed in the majority of subjects, indicating better targeting of clade-specific than conserved epitopes. The magnitude of CD8+ T cell responses to beneficial regions, together with viral entropy and HLA class I genotype, explained up to 59% of the variation in viral inhibitory activity, with magnitude of the T cell response making the strongest unique contribution. However, beneficial regions were infrequently targeted by CD8+ T cells elicited by vaccines encoding full-length HIV proteins, when the latter were administered to healthy volunteers and HIV-positive ART-treated subjects, suggesting that immunodominance hierarchies undermine effective anti-HIV CD8+ T cell responses. Taken together, our data support HIV immunogen design that is based on systematic selection of empirically defined vulnerable regions within the viral proteome, with exclusion of immunodominant decoy epitopes that are irrelevant for HIV control