Asier Sáez-Cirión

Post-Treatment HIV-1 Controllers with a Long-Term Virological Remission after the Interruption of Early Initiated Antiretroviral Therapy ANRS VISCONTI Study

Combination antiretroviral therapy (cART) reduces HIV-associated morbidities and mortalities but cannot cure the infection. Given the difficulty of eradicating HIV-1, a functional cure for HIV-infected patients appears to be a more reachable short-term goal. We identified 14 HIV patients (post-treatment controllers [PTCs]) whose viremia remained controlled for several years after the interruption of prolonged cART initiated during the primary infection. Most PTCs lacked the protective HLA B alleles that are overrepresented in spontaneous HIV controllers (HICs); instead, they carried risk-associated HLA alleles that were largely absent among the HICs. Accordingly, the PTCs had poorer CD8+ T cell responses and more severe primary infections than the HICs did. Moreover, the incidence of viral control after the interruption of early antiretroviral therapy was higher among the PTCs than has been reported for spontaneous control. Off therapy, the PTCs were able to maintain and, in some cases, further reduce an extremely low viral reservoir. We found that long-lived HIV-infected CD4+ T cells contributed poorly to the total resting HIV reservoir in the PTCs because of a low rate of infection of naïve T cells and a skewed distribution of resting memory CD4+ T cell subsets. Our results show that early and prolonged cART may allow some individuals with a rather unfavorable background to achieve long-term infection control and may have important implications in the search for a functional HIV cure.

HIV controllers exhibit potent CD8 T cell capacity to suppress HIV infection ex vivo and peculiar cytotoxic T lymphocyte activation phenotype

Some rare HIV-1-infected individuals, referred to as HIV controllers (HIC), have persistently undetectable plasma viral load in the absence of therapy. This control of HIV-1 replication has been associated with a strong, multifunctional specific CD8+ T cell response. However, no direct link between this immune response and the control of viremia has so far been provided. We investigated parameters of specific CD8+ T cell response and in vitro susceptibility to HIV-1 infection in 11 HIC. We found high frequencies of HIV-specific CD8+ T cells. Interestingly, these cells expressed the activation marker HLA-DR but not CD38. This unique phenotype differentiates HIV-specific CD8+ T cells from HIC and noncontroller subjects and likely reflects a high potential to expand upon exposure to antigen and a capacity to exert effector functions. Accordingly, although CD4+ T cells from HIC were fully susceptible to HIV-1 superinfection, their CD8+ T cells effectively suppressed HIV-1 infection. Remarkably, this potent anti-HIV activity was observed without prior stimulation of CD8+ T cells. This activity was not mediated by secreted inhibitory factors but was due to the elimination of infected CD4+ T cells and was observed only with autologous CD4+ T cells, indicating an HLA-restricted cytotoxic mechanism. This constitutive antiviral capacity of CD8+ T cells could account for the control of viral replication in HIC.

Heterogeneity in HIV Suppression by CD8 T Cells from HIV Controllers: Association with Gag-Specific CD8 T Cell Responses

“HIV controllers” (HICs) are rare individuals in whom HIV-1 plasma viral load remains undetectable without antiretroviral treatment. This spontaneous viral control in HICs is usually associated to strong functional HIV-specific CD8+ T cell responses. Accordingly, we have recently shown that CD8+ T cells from HICs strongly suppress ex vivo HIV-1 infection of autologous CD4+ T cells, suggesting a crucial role of this response in vivo. Knowledge of the mechanisms underlying the CD8+ T cell antiviral activity might help to develop effective T cell-based vaccines. In the present work, we further characterized the HIV-suppressive capacity of CD8+ T cells in 19 HICs. CD8+ T cells from 14 of the 19 HICs showed strong HIV-suppressive capacity ex vivo. This capacity was stable over time and was partially effective even on other primate lentiviruses. HIV-suppressive capacity of CD8+ T cells correlated strongly with the frequency of HIV-specific CD8+ T cells, and in particular of Gag-specific CD8+ T cells. We also identified five HICs who had weak HIV-suppressive CD8+ T cell capacities and HIV-specific CD8+ T cell responses. Among these five HICs, at least three had highly in vitro replicative viruses, suggesting that the control of viremia in these patients is not due to replication-defective viruses. These results, on the one hand, suggest the importance of Gag responses in the antiviral potency of CD8+ T cells from HICs and, on the other hand, propose that other host mechanisms may contribute to restraining HIV infection in HICs.

International AIDS Society global scientific strategy: towards an HIV cure 2016

Antiretroviral therapy is not curative. Given the challenges in providing lifelong therapy to a global population of more than 35 million people living with HIV, there is intense interest in developing a cure for HIV infection. The International AIDS Society convened a group of international experts to develop a scientific strategy for research towards an HIV cure. This Perspective summarizes the groups strategy.

Restriction of HIV-1 replication in macrophages and CD4+ T cells from HIV controllers

How HIV controllers (HICs) maintain undetectable viremia without therapy is unknown. The strong CD8(+) T-cell HIV suppressive capacity found in many, but not all, HICs may contribute to long-lasting viral control. However, other earlier defense mechanisms may be involved. Here, we examined intrinsic HIC cell resistance to HIV-1 infection. After in vitro challenge, monocyte-derived macrophages and anti-CD3-activated CD4(+) T cells from HICs showed low HIV-1 susceptibility. CD4 T-cell resistance was independent of HIV-1 coreceptors and affected also SIVmac infection. CD4(+) T cells from HICs expressed ex vivo higher levels of p21(Waf1/Cip1), which has been involved in the control of HIV-1 replication, than cells from control subjects. However, HIV restriction in anti-CD3-activated CD4(+) T cells and macrophages was not associated with p21 expression. Restriction inhibited accumulation of reverse transcripts, leading to reduction of HIV-1 integrated proviruses. The block could be overcome by high viral inocula, suggesting the action of a saturable mechanism. Importantly, cell-associated HIV-1 DNA load was extremely low in HICs and correlated with CD4(+) T-cell permissiveness to infection. These results point to a contribution of intrinsic cell resistance to the control of infection and the containment of viral reservoir in HICs.

Replication-competent HIV strains infect HIV controllers despite undetectable viremia (ANRS EP36 study).

The replicative potential of HIV-1 strains in a well-characterized group of eight HIV controllers was investigated. Replication-competent viruses were detected in CD4 T-cell co-culture supernatants from all HIV controllers. The phylogenetic analysis of C2V4 suggested viral evolution or co-infection or superinfection in two out of the four patients analysed. The vif and vpr genes were normal. Infection with HIV-1 variants with attenuated replicative capacity cannot be a general factor accounting for undetectable viraemia in HIV controllers.

HIV cure research: Advances and prospects

Thirty years after the identification of HIV, a cure for HIV infection is still to be achieved. Advances of combined antiretroviral therapy (cART) in recent years have transformed HIV infection into a chronic disease when treatment is available. However, in spite of the favorable outcomes provided by the newer therapies, cART is not curative and patients are at risk of developing HIV-associated disorders. Moreover, universal access to antiretroviral treatment is restricted by financial obstacles. This review discusses the most recent strategies that have been developed in the search for an HIV cure and to improve life quality of people living with HIV.

Elevated IP10 levels are associated with immune activation and low CD4⁺ T-cell counts in HIV controller patients

Background:Although HIV controllers (HICs) achieve long-term control of viremia in the absence of antiretroviral therapy (ART), they display marked immune activation. The levels of inflammatory biomarkers in HICs and the biomarkers’ relationships with immunologic and virologic status have yet to be fully characterized. Design:A cohort study. Methods:Plasma levels of seven biomarkers [tumor necrosis factor (TNF)&agr;, interleukin (IL)6, IL10, interferon gamma-induced protein 10 (IP10), monocyte chemoattractant protein-1 (MCP1), soluble CD14 (sCD14), soluble CD163 (sCD163)] were compared in 70 HICs, 33 HIV-1-infected, treatment-naive noncontrollers (viremic patients), 30 ART-treated patients and 40 healthy donors. In HICs, we investigated the interplay between biomarkers, cell activation and the CD4+ T-cell count. Results:HICs had higher levels of IP10, TNF&agr; and sCD14 than healthy donors did (P < 0.01 for each). Also, TNF&agr; and sCD14 levels of the HICs were similar to those measured in viremic and ART-treated patients. However, the levels of IL6 and IL10 were significantly lower in HICs than in viremic or ART-treated patients. In HICs, only IP10 levels differed significantly from those in both healthy donors and viremic patients, and were positively correlated with the expression of CD8+ and CD4+ T-cell activation markers. The IP10 levels of HICs were still elevated 12 and 24 months after the initial assay. Lastly, IP10 levels at enrollment were negatively correlated with the CD4+ T-cell count at enrollment and 12 months later. Conclusion:HICs display a number of inflammatory features associated with persistent T-cell immune activation.

p21-mediated RNR2 repression restricts HIV-1 replication in macrophages by inhibiting dNTP biosynthesis pathway

Significance Macrophages, with CD4+ T lymphocytes, are a major cell target for HIV-1 infection. We have previously reported that the induction of a cellular protein, the cyclin-dependent kinase p21, inhibits HIV-1 replication in macrophages. We now show that p21 impairs the reverse transcription of HIV-1 and other primate lentiviruses, including the simian immunodeficiency virus (SIV)mac, by blocking the synthesis of cellular deoxynucleotides (dNTP) that are used by retroviral reverse transcriptase for viral DNA synthesis. p21 represses the expression of a key enzyme of the dNTP biosynthesis pathway, the RNR2 subunit of the ribonucleotide reductase. Our findings point to new potential cellular targets for antiretroviral strategies. Macrophages are a major target cell for HIV-1, and their infection contributes to HIV pathogenesis. We have previously shown that the cyclin-dependent kinase inhibitor p21 inhibits the replication of HIV-1 and other primate lentiviruses in human monocyte-derived macrophages by impairing reverse transcription of the viral genome. In the attempt to understand the p21-mediated restriction mechanisms, we found that p21 impairs HIV-1 and simian immunodeficiency virus (SIV)mac reverse transcription in macrophages by reducing the intracellular deoxyribonucleotide (dNTP) pool to levels below those required for viral cDNA synthesis by a SAM domain and HD domain-containing protein 1 (SAMHD1)-independent pathway. We found that p21 blocks dNTP biosynthesis by down-regulating the expression of the RNR2 subunit of ribonucleotide reductase, an enzyme essential for the reduction of ribonucleotides to dNTP. p21 inhibits RNR2 transcription by repressing E2F1 transcription factor, its transcriptional activator. Our findings unravel a cellular pathway that restricts HIV-1 and other primate lentiviruses by affecting dNTP synthesis, thereby pointing to new potential cellular targets for anti-HIV therapeutic strategies.

Ex vivo T cell–based HIV suppression assay to evaluate HIV-specific CD8 + T-cell responses

To advance T cell–based HIV vaccine development, it is necessary to evaluate the immune correlates of a protective CD8+ T-cell response. We have developed an assay that assesses the capacity ex vivo of HIV-specific CD8+ T cells to suppress HIV-1 infection of autologous CD4+ T cells. This assay directly reflects the ultimate effector function of CD8+ T cells, the elimination of infected cells, and accurately differentiates the effective CD8+ T-cell response in spontaneous HIV controllers from ineffective responses in other patients. In this article, we describe all the steps from cell purification to assessment of viral replication by HIV-p24 ELISA and analysis, along with conditions for cell culturing, and how to choose the viral infectious dose that gives the most reliable results. We also depict the conditions of a rapid assay on the basis of flow cytometry analysis of intracellular HIV-Gag products. These procedures take 14–17 d when the p24 ELISA assay is used, or 6 d with the intracellular Gag assay.