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Despite the success of antiretroviral therapy (ART) in reducing HIV-1–related morbidity and mortality, viral reservoirs persist in infected cells in individuals on suppressive ART. Unfortunately, very few therapeutic strategies have led to a substantial decrease in the number of these persistently infected cells, and novel approaches to eliminate or reduce HIV reservoir burden are urgently needed.1 One such high-priority strategy is the identification of cell-surface markers of either quiescent or HIV-1 transcriptionally active cells that may be targeted with therapeutics such as cytotoxic antibody-drug conjugates (ADCs).2,3 Whereas the search for targetable biomarkers on quiescent, latently infected cells has remained elusive, an alternative approach involves targeting and clearing viral reactivated cells following in vivo HIV-1 latency reversal, thereby providing the “kill” component to the “shock-and-kill” approach to achieving a functional HIV-1 cure or long-term ART-free remission.2,3 We recently reported that CD4+ T cells expressing CD30, a cell-surface membrane protein and a member of the tumor necrosis factor receptor superfamily, were enriched in HIV-1 RNA, and that CD30 and HIV-1 transcriptional activity strongly colocalized in gut tissue from ART-suppressed individuals.2 Furthermore, HIV-1–infected individuals, either viremic or on suppressive ART, had significantly higher percentages of memory CD4+ T cells that expressed CD30 compared with uninfected controls.2 Prior studies also demonstrated a link between HIV-1 plasma RNA and disease progression with soluble plasma CD30 levels.4-8 CD30 is usually expressed on tumor cells involved with Hodgkin or aggressive lymphomas, but is otherwise expressed in very few cells from healthy, HIV-1–uninfected individuals,9,10 making it an enticing target. We have also observed that ex vivo treatment of peripheral blood mononuclear cells (PBMCs) from ART-suppressed individuals with brentuximab vedotin, an anti-CD30 ADC,11 led to a decrease in HIV-1 DNA levels in samples from 4 of 7 participants tested.2 However, the direct, longitudinal impact of brentuximab vedotin therapy on measures of HIV-1 persistence in vivo is not known and proof-of-concept studies are urgently needed. Therefore, we studied the impact of 3 doses of brentuximab vedotin therapy for Hodgkin lymphoma on HIV-1 persistence and immune phenotype in a newly identified HIV-1–infected individual on long-term ART.

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International audience; The persistence of the HIV reservoir in infected individuals is a major obstacle to the development of a cure for HIV. Here, using an in vitro model of HIV-infected quiescent CD4 T cells, we reveal a gene expression signature of 103 upregulated genes that are specific for latently infected cells, including genes for 16 transmembrane proteins. In vitro screening for surface expression in HIV-infected quiescent CD4 T cells shows that the low-affinity receptor for the immunoglobulin G Fc fragment, CD32a, is the most highly induced, with no detectable expression in bystander cells. Notably, productive HIV-1 infection of T-cell-receptor-stimulated CD4 T cells is not associated with CD32a expression, suggesting that a quiescence-dependent mechanism is required for its induction. Using blood samples from HIV-1-positive participants receiving suppressive antiretroviral therapy, we identify a subpopulation of 0.012% of CD4 T cells that express CD32a and host up to three copies of HIV DNA per cell. This CD32a+ reservoir was highly enriched in inducible replication-competent proviruses and can be predominant in some participants. Our discovery that CD32a+ lymphocytes represent the elusive HIV-1 reservoir may lead to insights that will facilitate the specific targeting and elimination of this reservoir.

Objectives: The aim of the study was to determine the molecular mechanisms underlying the quasi-equilibrium between HIV and its host in the model of functional cure represented by elite controllers who spontaneously maintain exceptionally low levels of HIV reservoirs. Design: Whole-genome transcriptional study and quantification of the cell-associated HIV DNA and HIV RNA levels of the four major resting CD4 þ T-cell subsets in HIV-1infected elite controllers, viremic long-term nonprogressors (vir-LTNPs), and uninfected individuals. Methods: We compared the whole-genome transcriptional profiles (ArrayExpress accession number E-MTAB-1480) of the four major resting CD4 þ T-cell subsets [naive (TN), central-memory (TCM), transitional-memory (TTM), and effector-memory (TEM)] from 14 HIV-1-infected individuals including seven elite controllers (E-LTNPs) and seven vir-LTNPs, and from seven uninfected individuals. The HIV-1 cellular DNA and mRNA levels were quantified in parallel in each sorted subset. Results: Host genetranscriptomes followed subset differentiation and viremia exceptin E-LTNPs wherein TCM, the main CD4 þ cell compartment, showed the highest activity with three specific signatures involving overexpression of T-cell receptor and costimulation signaling pathways, overexpression of the PRDM-1/Blimp-1 transcriptional repressor, and downmodulation of type-I IFN-related genes. Among subsets, the PRDM1/Blimp-1 upregulation was associated with lower levels of both cellular HIV-DNA and HIV mRNA levels. Conclusion: This unique Blimp-1 transcriptional repressor signature and the contrast between host and virus transcriptional activities in TCM from elite controllers suggest Blimp-1 might be involved in controlling the HIV reservoirs in the key TCM subset. 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins AIDS 2014, 28:1567‐1577

Massive activation of infected CD4+ T cells during acute HIV-1 infection leads to reservoir seeding and T-cell destruction. During T-cell activation, the antiviral effect of the innate factor SAMHD1 is neutralized through phosphorylation at T592, allowing HIV-1 infection. Dasatinib, a tyrosine kinase inhibitor currently used for treating chronic myeloid leukemia, has been described to control HIV-1 replication through its negative effect on T-cell proliferation and viral entry. We demonstrate that Dasatinib can actually interfere with SAMHD1 phosphorylation in human peripheral blood lymphocytes, preserving its antiviral activity against HIV-1. Dasatinib prevented SAMHD1 phosphorylation in vitro and ex vivo, impairing HIV-1 reverse transcription and proviral integration. This was the major mechanism of action because the presence of Vpx, which degrades SAMHD1, in HIV-1 virions impeded the inhibitory effect of Dasatinib on HIV-1 replication. In fact, infection with VSV-pseudotyped HIV-1 virions and fusion of BlaM-Vpr-containing HIV-1 viruses with activated PBMCs in the presence of Dasatinib suggested that Dasatinib was not acting at fusion level. Finally, PBMCs from patients on chronic treatment with Dasatinib showed a lower level of SAMHD1 phosphorylation in response to activating stimuli and low susceptibility to HIV-1 infection ex vivo. Consequently, Dasatinib is a compound currently used in clinic that preserves the antiviral function of SAMHD1. Using Dasatinib as adjuvant of antiretroviral therapy during early primary HIV-1 infection would contribute to reduce viral replication and spread, prevent reservoir seeding, and preserve CD4 counts and CTL responses. These events would create a more favorable virologic and immunologic environment for future interventional studies aiming at HIV-1 eradication. This work was supported by the Spanish Ministry of Economy and Competitiveness (SAF2010-18388, SAF2013-44677-R, FIS PI12/00506, and FIS PI12/00969); the SPANISH AIDS Research Network RD12/0017/0015 that is included in Acción Estratégica en Salud, Plan Nacional de Investigación Científica, Desarrollo e Innovación Tecnológica 2008-2011, Instituto de Salud Carlos III, European Region Development Fund (ERDF); Bristol-Myers Squibb (BMS AI471-041); AIM-HIV Network of Excellence of the EU, grant number HEALTH-F3-2012-305938; joined program of the Agence Nationale de Recherches sur le SIDA et les Hépatites Virales (ANRS AO2014-2); and the European FP7-HEALTH project HIT HIDDEN HIV. The work of Elena Mateos is supported by the Instituto de Salud Carlos III (Spain) (MPY 1371/12). The work of Sara Rodríguez-Mora is supported by a fellowship of Sara Borrell from Spanish Ministry of Economy and Competitiveness. The work of María Rosa López-Huertas is supported by a fellowship of the European Union Programme Health 2009 (CHAARM). The work of Dr Benjamin Descours is supported by the 31 European FP7-HEALTH project HIT HIDDEN HIV. Dr. Montserrat Plana is a researcher at the Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) and is supported by the Spanish Health Institute Carlos III (ISCIII) and the Health Department of the Catalan Government (Generalitat de Catalunya). Dr. Juan Ambrosioni developed this work in the framework of a ‘Juan de la Cierva 2012’ post- doctoral program, Ministerio de Competitividad, Madrid, Spain. Sí

The limitations of life-long antiretroviral therapies for the HIV infection lead to a novel concept of a functional cure developing innovative therapeutic strategies to generate a long-term remission of HIV replication without treatment. This concept requires an understanding of the mechanisms by which HIV is controlled in conditions of undetectable virus replication, before developing ambitious therapies blocking durably viral replication - and ultimately eradicating HIV.Recent literature shows that the exceptional elite controller status is usually not driven by virus gross genetic defects, despite some virus attenuation resulting from immune selective pressure, but is frequently determined by host's genetic factors permitting robust cell-mediated immunity to control the virus replication and reservoirs. Lack of immunity and immune deficiency can however limit this model in some cases and only a subgroup in whom both the virus and the immune deficiency are controlled, that is the elite long-term controllers, might represent the best current model for a functional cure.This review examines whether the exceptional HIV-infected elite controllers, who spontaneously and durably maintain extremely low virus replication, might be considered as a model for a functional cure and whether the mechanisms identified in these exceptional individuals might serve to identify therapeutic or vaccine strategies.

SUMMARY HIV-1 post-integration latency in CD4+ lymphocytes is responsible for viral persistence despite treatment, but mechanisms involved in the establishment of latent viral reservoirs are not fully understood. We determined that both interleukin 2 (IL-2) and IL-7 induced SAMHD1 phosphorylation in T592, abrogating its antiviral activity. However, IL-7 caused a much more profound stimulatory effect on HIV-1 reverse transcription and integration than IL-2 that required chemokine co-stimulation. Both cytokines barely induced transcription due to low NF-κB induction, favoring the establishment of latent reservoirs. Effect of IL-7 on SAMHD1 phosphorylation was confirmed in IL-7-treated patients (ACTG 5214 study). Dasatinib—a tyrosine-kinase inhibitor—blocked SAMHD1 phosphorylation induced by IL-2 and IL-7 and restored HIV-1 restriction. We propose that γc-cytokines play a major role in the reservoir establishment not only by driving homeostatic proliferation but also by increasing susceptibility of CD4+ lymphocytes to HIV-1 infection through SAMHD1 inactivation., In Brief Coiras et al. show that IL-2 and IL-7 induce SAMHD1 phosphorylation, abrogating its antiviral activity. This increases susceptibility of CD4+ lymphocytes to HIV-1 infection, contributing to the establishment of the reservoir. These γc-cytokines also maintain the reservoir through homeostatic proliferation. The tyrosine-kinase inhibitor dasatinib blocked SAMHD1 phosphorylation induced by IL-2 and IL-7, restoring HIV-1 restriction.

Nature 543, 564–567 (2017); doi:10.1038/nature21710 In the Acknowledgements section, the European FP7 contract number was incorrect in two places; it should be 305762. The original Letter has been corrected online.

Purpose of review To discuss the recent major advances in the understanding of how host immune defenses contribute to HIV reservoir control. Recent findings Immune control of HIV-1 reservoirs is a two-step process: viral replication activation from latent reservoirs followed by elimination of virus-expressing cells by the host. Environmental factors, such as pro-inflammatory type-I interferon, chemokines or cytokines, can facilitate HIV-1 replication, confer dormancy in CD4 cells or confer resistance to cytopathogenic effects of cytotoxic CD8 T cells. Therefore, they constitute a double-edged sword for immune control of HIV reservoirs. Concomitantly, adaptive immunity takes advantage of CD4 T-cell homeostatic mechanisms and can expose HIV-1 antigen-expressing cells to HIV-specific cytotoxic CD8 T cells, and limit virus spreading. These highly interconnected phenomena can lead to quasi-equilibrium between the HIV-1 reservoirs and host immune control that can serve as a model for the 'shock and kill' immune-based therapeutic strategies in play in the course of finding an HIV cure. Summary Immune control of HIV reservoirs in CD4 T cells involves modulation of both HIV-1 latency and the continuous reseeding of the reservoir offering conceptual models that may advance HIV cure strategies.

To evaluate the contribution of CD4 T cells from blood and gut compartments to the HIV-1 reservoir, we directly quantified cell-associated HIV DNA in isolated rectal (R-) and peripheral blood (PB-) memory CD4 T cells from 11 successfully long-term treated patients. Proportion of activated (CD25(+); CD69(+); and HLA-DR(+)) and CCR5 expressing CD4 T cells were markedly higher in rectal tissue compared with blood. However, HIV-1 infection levels of R- and PB-memory CD4 T cells did not significantly differ (medians: 4000 and 2100 copies per million cells) after effective long-term viral control, suggesting that each of these 2 compartments does not contribute in a similar fashion to the total HIV reservoir.

Background Quiescent CD4+ T lymphocytes are highly refractory to HIV-1 infection due to a block at reverse transcription. Results Examination of SAMHD1 expression in peripheral blood lymphocytes shows that SAMHD1 is expressed in both CD4+ and CD8+ T cells at levels comparable to those found in myeloid cells. Treatment of CD4+ T cells with Virus-Like Particles (VLP) containing Vpx results in the loss of SAMHD1 expression that correlates with an increased permissiveness to HIV-1 infection and accumulation of reverse transcribed viral DNA without promoting transcription from the viral LTR. Importantly, CD4+ T-cells from patients with Aicardi-Goutières Syndrome harboring mutation in the SAMHD1 gene display an increased susceptibility to HIV-1 infection that is not further enhanced by VLP-Vpx-treatment. Conclusion Here, we identified SAMHD1 as the restriction factor preventing efficient viral DNA synthesis in non-cycling resting CD4+ T-cells. These results highlight the crucial role of SAMHD1 in mediating restriction of HIV-1 infection in quiescent CD4+ T-cells and could impact our understanding of HIV-1 mediated CD4+ T-cell depletion and establishment of the viral reservoir, two of the HIV/AIDS hallmarks.

Background. The stable immune control of human immunodeficiency virus (HIV) in long-term nonprogressors (LTNPs) with protective human leukocyte antigen (HLA) alleles raises the question of whether and how these alleles influence the immune distribution of the HIV reservoirs. Methods. Cell-associated HIV-DNA levels were quantified in blood sorted resting CD4 T-cell subsets from 8 LTNPs with and 10 without HLA-B*27 or HLA-B*57 alleles (HLA-B27/B57). Results. A remarkably lower infection level of central memory CD4 T cells (TCM) was an exclusive feature that distinguished the HLA-B27/B57 HIV reservoirs from the other ones. In LTNPs, TCM protection was correlated with preservation of TCM counts, which correlated positively with the magnitude of HIV Gag-specific CD8 T cells. In HLAB27/B57 LTNPs, a lower activation level of their memory CD4 T cells was associated with lower amounts of cell HIV-DNA in each resting memory CD4 subset and were also associated with higher ratios of HIV Gag-specific CD8 T cells per infected resting CD4 T cell (effector/target [E/T]). As a result, HLA-B27/B57 E/T ratios were negatively correlated with the contribution of memory CD4 T-cell subsets to the total HIV reservoirs. Conclusions. The potent antiviral immunity governed by the protective HLA-B27/B57 alleles, by limiting TCM infection and pool exhaustion, are associated with a reduced TCM contribution to the HIV reservoir. Host genes are instrumental in the effective multifactorial long-term control of human immunodeficiency virus (HIV)‐1 replication observed in some rare HIVinfected individuals (ie, long-term nonprogressors [LTNPs] or elite controllers [ECs]). The major histocompatibility complex class I (MHC-I) alleles such as

The bone marrow (BM) has been identified as a possible organ for T cell priming, yet the fundamental mechanisms of a polyclonal immune response in the BM remain unknown. We found that after intradermal injection of modified vaccinia Ankara virus, unexpected sources of newly primed polyclonal virus-specific CD8(+), but not CD4(+), T cells were localized in the BM and the draining lymph nodes (dLNs) prior to blood circulation. We identified neutrophils as the virus-carrier cells from the dermis to the BM. In both neutrophil-depleted and Ccr1(-/-) mice, virus-specific BM CD8(+) responses were lost. Myeloid antigen-presenting cells were required for BM CD8(+) T cell priming. A systems biology analysis of dLN and BM virus-specific CD8(+) T cells revealed distinct transcriptional and multifunctional profiles for cells primed in each organ. We provide direct evidence for how antigen is transported to the BM, providing a source of virus-specific memory CD8(+) T cells.

Background Terminal differentiation of NK cells is crucial in maintaining broad responsiveness to pathogens and discriminating normal cells from cells in distress. Although it is well established that KIRs, in conjunction with NKG2A, play a major role in the NK cell education that determines whether cells will end up competent or hyporesponsive, the events underlying the differentiation are still debated. Methodology/Principal Findings A combination of complementary approaches to assess the kinetics of the appearance of each subset during development allowed us to obtain new insights into these terminal stages of differentiation, characterising their gene expression profiles at a pan-genomic level, their distinct surface receptor patterns and their prototypic effector functions. The present study supports the hypothesis that CD56dim cells derive from the CD56bright subset and suggests that NK cell responsiveness is determined by persistent inhibitory signals received during their education. We report here the inverse correlation of NKG2A expression with KIR expression and explore whether this correlation bestows functional competence on NK cells. We show that CD56dimNKG2A−KIR+ cells display the most differentiated phenotype associated to their unique ability to respond against HLA-E+ target cells. Importantly, after IL-12 + IL-18 stimulation, reacquisition of NKG2A strongly correlates with IFN-γ production in CD56dimNKG2A− NK cells. Conclusions/Significance Together, these findings call for the reclassification of mature human NK cells into distinct subsets and support a new model, in which the NK cell differentiation and functional fate are based on a stepwise decrease of NKG2A and acquisition of KIRs.

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International audience; SAMHD1 restricts HIV-1 replication in myeloid andquiescent CD4+T cells. Here, we show that SAMHD1restriction activity is regulated by phosphorylation.SAMHD1 interacts with cyclin A2/cdk1 only in cyclingcells. Cyclin A2/CDK1 phosphorylates SAMHD1 atthe Threonine 592 residue both in vitro and in vivo.Phosphorylation of SAMHD1 Thr592 correlates withloss of its ability to restrict HIV-1. Indeed, whilePMA treatment of proliferating THP1 cells results inreduced Thr592 phosphorylation, activation ofresting peripheral blood mononuclear cells (PBMCs)and purified quiescent CD4+T cells results inincreased phosphorylation of SAMHD1 Thr592. Inter-estingly, we found that treatment of cells by type 1interferon reduced Thr592 phosphorylation, reinforc-ing the link between the phosphorylation of SAMHD1and its antiviral activity. Unlike wild-type SAMHD1,a phosphorylation-defective mutant was able torestrict HIV-1 replication in both PMA-treatedand untreated cells. Our results uncover the phos-phorylation of SAMHD1 at Thr592 by cyclin A2/CDK1 as a key regulatory mechanism of its antiviralactivity.