Post-treatment HIV-1 controllers with a long-term virological remission after the interruption of early initiated antiretroviral therapy ANRS VISCONTI Study

CRISPR editing of CCR5 and HIV-1 facilitates viral elimination in antiretroviral drug-suppressed virus-infected humanized mice

Treatment of HIV-1ADA-infected CD34+ NSG-humanized mice with long-acting ester prodrugs of cabotegravir, lamivudine, and abacavir in combination with native rilpivirine was followed by dual CRISPR-Cas9 C-C chemokine receptor type five (CCR5) and HIV-1 proviral DNA gene editing. This led to sequential viral suppression, restoration of absolute human CD4+ T cell numbers, then elimination of replication-competent virus in 58% of infected mice. Dual CRISPR therapies enabled the excision of integrated proviral DNA in infected human cells contained within live infected animals. Highly sensitive nucleic acid nested and droplet digital PCR, RNAscope, and viral outgrowth assays affirmed viral elimination. HIV-1 was not detected in the blood, spleen, lung, kidney, liver, gut, bone marrow, and brain of virus-free animals. Progeny virus from adoptively transferred and CRISPR-treated virus-free mice was neither detected nor recovered. Residual HIV-1 DNA fragments were easily seen in untreated and viral-rebounded animals. No evidence of off-target toxicities was recorded in any of the treated animals. Importantly, the dual CRISPR therapy demonstrated statistically significant improvements in HIV-1 cure percentages compared to single treatments. Taken together, these observations underscore a pivotal role of combinatorial CRISPR gene editing in achieving the elimination of HIV-1 infection.

HIV infection dynamics and viral rebound: Modeling results from humanized mice

Despite years of combined antiretroviral therapy (cART), HIV persists in infected individuals. The virus also rebounds after the cessation of cART. The sources contributing to viral persistence and rebound are not fully understood. When viral rebound occurs, what affects the time to rebound and how to delay the rebound remain unclear. In this paper, we started with the data fitting of an HIV infection model to the viral load data in treated and untreated humanized myeloid-only mice (MoM) in which macrophages serve as the target of HIV infection. By fixing the parameter values for macrophages from the MoM fitting, we fit a mathematical model including the infection of two target cell populations to the viral load data from humanized bone marrow/liver/thymus (BLT) mice, in which both CD4+ T cells and macrophages are the target of HIV infection. Data fitting suggests that the viral load decay in BLT mice under treatment has three phases. The loss of infected CD4+ T cells and macrophages is a major contributor to the first two phases of viral decay, and the last phase may be due to the latent infection of CD4+ T cells. Numerical simulations using parameter estimates from the data fitting show that the pre-ART viral load and the latent reservoir size at treatment cessation can affect viral growth rate and predict the time to viral rebound. Model simulations further reveal that early and prolonged cART can delay the viral rebound after cessation of treatment, which may have implications in the search for functional control of HIV infection.

HIV persistence: silence or resistance?

Despite decades of suppressive antiretroviral therapy, human immunodeficiency virus (HIV) reservoirs in infected individuals persist and fuel viral rebound once therapy is interrupted. The persistence of viral reservoirs is the main obstacle to achieving HIV eradication or a long-term remission. The last decade has seen a profound change in our understanding of the mechanisms behind HIV persistence, which appears to be much more complex than originally assumed. In addition to the persistence of transcriptionally silent proviruses in a stable latent reservoir that is invisible to the immune system, HIV is increasingly recognized to persist by resistance to the immune clearance, which appears to play a surprisingly prominent role in shaping the reservoir. In this review, we discuss some emerging insights into the mechanisms of HIV persistence, as well as their implications for the development of strategies towards an HIV cure.

Factors associated with post-treatment control of viral load in HIV-infected patients: a systematic review and meta-analysis

OBJECTIVES

This study aimed to investigate the factors associated with maintenance of viral suppression after antiretroviral therapy (ART) discontinuation.

METHODS

Databases were searched for studies published between January 01, 2011, and July 01, 2022, that correlated the time of virus rebound with treatment interruption (TI). The corresponding data were extracted from these studies. A fixed-effects model was used to calculate pooled estimates.

RESULTS

Thirty-one studies were included in this analysis. Results showed that patients who started ART during acute or early infection had longer viral control than those who started ART during chronic infection. It has been reported that some broadly neutralizing HIV-1-specific antibodies can significantly prolong viral inhibition. The study also found that approximately 7.2% of patients achieved post-treatment control (PTC) approximately a year after TI.

CONCLUSION

ART initiation in the acute or early phases can delay viral rebound after TI. Cell-associated HIV RNA and HIV DNA have been difficult to prove as able to predict viral rebound time. Many vaccines and antibodies have also been shown to be effective in prolonging viral control in people without PTC, and more research is needed to develop alternative ART therapies that can effectively inhibit or even eliminate HIV.

Advances in HIV Research Using Mass Cytometry

PURPOSE OF REVIEW

This review describes how advances in CyTOF and high-dimensional analysis methods have furthered our understanding of HIV transmission, pathogenesis, persistence, and immunity.

RECENT FINDINGS

CyTOF has generated important insight on several aspects of HIV biology: (1) the differences between cells permissive to productive vs. latent HIV infection, and the HIV-induced remodeling of infected cells; (2) factors that contribute to the persistence of the long-term HIV reservoir, in both blood and tissues; and (3) the impact of HIV on the immune system, in the context of both uncontrolled and controlled infection. CyTOF and high-dimensional analysis tools have enabled in-depth assessment of specific host antigens remodeled by HIV, and have revealed insights into the features of HIV-infected cells enabling them to survive and persist, and of the immune cells that can respond to and potentially control HIV replication. CyTOF and other related high-dimensional phenotyping approaches remain powerful tools for translational research, and applied HIV to cohort studies can inform on mechanisms of HIV pathogenesis and persistence, and potentially identify biomarkers for viral eradication or control.

Opportunities for CAR-T Cell Immunotherapy in HIV Cure

Chimeric antigen receptor (CAR) technology is having a huge impact in the blood malignancy field and is becoming a well-established therapy for many types of leukaemia. In recent decades, efforts have been made to demonstrate that CAR-T cells have potential as a therapy to achieve a sterilizing cure for human immunodeficiency virus (HIV) infection. However, translation of this technology to the HIV scenario has not been easy, as many challenges have appeared along the way that hinder the consolidation of CAR-T cells as a putative therapy. Here, we review the origin and development of CAR-T cells, describe the advantages of CAR-T cell therapy in comparison with other therapies, and describe the major obstacles currently faced regarding application of this technology in the HIV field, specifically, viral escape, CAR-T cell infectivity, and accessibility to hidden reservoirs. Nonetheless, promising results in successfully tackling some of these issues that have been obtained in clinical trials suggest a bright future for CAR-T cells as a consolidated therapy.

Role of microglia in HIV-1 infection

The usage of antiretroviral treatment (ART) has considerably decreased the morbidity and mortality related to HIV-1 (human immunodeficiency virus type 1) infection. However, ART is ineffective in eradicating the virus from the persistent cell reservoirs (e.g., microglia), noticeably hindering the cure for HIV-1. Microglia participate in the progression of neuroinflammation, brain aging, and HIV-1-associated neurocognitive disorder (HAND). Some methods have currently been studied as fundamental strategies targeting microglia. The purpose of this study was to comprehend microglia biology and its functions in HIV-1 infection, as well as to look into potential therapeutic approaches targeting microglia.

HIV post-treatment controllers have distinct immunological and virological features

HIV post-treatment controllers (PTCs) are rare individuals who maintain low levels of viremia after stopping antiretroviral therapy (ART). Understanding the mechanisms of HIV post-treatment control will inform development of strategies aiming at achieving HIV functional cure. In this study, we evaluated 22 PTCs from 8 AIDS Clinical Trials Group (ACTG) analytical treatment interruption (ATI) studies who maintained viral loads ≤400 copies/mL for ≥24 wk. There were no significant differences in demographics or frequency of protective and susceptible human leukocyte antigen (HLA) alleles between PTCs and post-treatment noncontrollers (NCs, n = 37). Unlike NCs, PTCs demonstrated a stable HIV reservoir measured by cell-associated RNA (CA-RNA) and intact proviral DNA assay (IPDA) during analytical treatment interruption (ATI). Immunologically, PTCs demonstrated significantly lower CD4+ and CD8+ T cell activation, lower CD4+ T cell exhaustion, and more robust Gag-specific CD4+ T cell responses and natural killer (NK) cell responses. Sparse partial least squares discriminant analysis (sPLS-DA) identified a set of features enriched in PTCs, including a higher CD4+ T cell% and CD4+/CD8+ ratio, more functional NK cells, and a lower CD4+ T cell exhaustion level. These results provide insights into the key viral reservoir features and immunological profiles for HIV PTCs and have implications for future studies evaluating interventions to achieve an HIV functional cure.

Immunomodulatory Activity of the Tyrosine Kinase Inhibitor Dasatinib to Elicit NK Cytotoxicity against Cancer, HIV Infection and Aging

Tyrosine kinase inhibitors (TKIs) have been extensively used as a treatment for chronic myeloid leukemia (CML). Dasatinib is a broad-spectrum TKI with off-target effects that give it an immunomodulatory capacity resulting in increased innate immune responses against cancerous cells and viral infected cells. Several studies reported that dasatinib expanded memory-like natural killer (NK) cells and γδ T cells that have been related with increased control of CML after treatment withdrawal. In the HIV infection setting, these innate cells are associated with virus control and protection, suggesting that dasatinib could have a potential role in improving both the CML and HIV outcomes. Moreover, dasatinib could also directly induce apoptosis of senescence cells, being a new potential senolytic drug. Here, we review in depth the current knowledge of virological and immunogenetic factors associated with the development of powerful cytotoxic responses associated with this drug. Besides, we will discuss the potential therapeutic role against CML, HIV infection and aging.

CD8+ cells and small viral reservoirs facilitate post-ART control of SIV in Mauritian cynomolgus macaques

Sustainable HIV remission after antiretroviral therapy (ART) withdrawal, or post-treatment control (PTC), remains a top priority for HIV treatment. We observed surprising PTC in an MHC-haplomatched cohort of MHC-M3+ SIVmac239+ Mauritian cynomolgus macaques (MCMs) initiated on ART at two weeks post-infection (wpi). For six months after ART withdrawal, we observed undetectable or transient viremia in seven of eight MCMs. In vivo depletion of CD8α+ cells induced rebound in all animals, indicating the PTC was mediated, at least in part, by CD8α+ cells. We found that MCMs had smaller acute viral reservoirs than a cohort of identically infected rhesus macaques, a population that rarely develops PTC. The mechanisms by which unusually small viral reservoirs and CD8α+ cell-mediated virus suppression enable PTC can be investigated using this MHC-haplomatched MCM model. Further, defining the immunologic mechanisms that engender PTC in this model may identify therapeutic targets for inducing durable HIV remission in humans.

In-Depth Characterization of Full-Length Archived Viral Genomes after Nine Years of Posttreatment HIV Control

In the search for control of human immunodeficiency virus type 1 (HIV-1) infection without antiretroviral therapy, posttreatment controllers (PTCs) are models of HIV remission. To better understand their mechanisms of control, we characterized the HIV blood reservoirs of 8 PTCs (median of 9.4 years after treatment interruption) in comparison with those of 13 natural HIV infection controllers (HICs) (median of 18 years of infection) and with those of individuals receiving efficient antiretroviral therapy initiated during either primary HIV infection (PHIs; n = 8) or chronic HIV infection (CHIs; n = 6). This characterization was performed with single-genome amplification and deep sequencing. The proviral diversity, which reflects the history of past viral replication, was lower in the PTCs, PHIs, and aviremic HICs than in the blipper HICs and CHIs. The proportions of intact and defective proviruses among the proviral pool in PTCs were not significantly different from those of other groups. When looking at the quantities of proviruses per million peripheral blood mononuclear cells (PBMCs), they had similar amounts of intact proviruses as other groups but smaller amounts of defective proviruses than CHIs, suggesting a role of these forms in HIV pathogenesis. Two HICs but none of the PTCs harbored only proviruses with deletion in nef; these attenuated strains could contribute to viral control in these participants. We show, for the first time, the presence of intact proviruses and low viral diversity in PTCs long after treatment interruption, as well as the absence of evolution of the proviral quasispecies in subsequent samples. This reflects low residual replication over time. Further data are necessary to confirm these results. IMPORTANCE Most people living with HIV need antiretroviral therapy to control their infection and experience viral relapse in case of treatment interruption, because of viral reservoir (proviruses) persistence. Knowing that proviruses are very diverse and most of them are defective in treated individuals, we aimed to characterize the HIV blood reservoirs of posttreatment controllers (PTCs), rare models of drug-free remission, in comparison with spontaneous controllers and treated individuals. At a median time of 9 years after treatment interruption, which is unprecedented in the literature, we showed that the proportions and quantities of intact proviruses were similar between PTCs and other individuals. Unlike 2/7 spontaneous controllers who harbored only nef-deleted proviruses, which are attenuated strains, which could contribute to their control, no such case was observed in PTCs. Furthermore, PTCs displayed low viral genetic diversity and no evolution of their reservoirs, indicating very low residual replication, despite the presence of intact proviruses.

Slow progression of pediatric HIV associates with early CD8+ T cell PD-1 expression and a stem-like phenotype

HIV nonprogression despite persistent viremia is rare among adults who are naive to antiretroviral therapy (ART) but relatively common among ART-naive children. Previous studies indicate that ART-naive pediatric slow progressors (PSPs) adopt immune evasion strategies similar to those described in natural hosts of SIV. However, the mechanisms underlying this immunophenotype are not well understood. In a cohort of early-treated infants who underwent analytical treatment interruption (ATI) after 12 months of ART, expression of PD-1 on CD8+ T cells immediately before ATI was the main predictor of slow progression during ATI. PD-1+CD8+ T cell frequency was also negatively correlated with CCR5 and HLA-DR expression on CD4+ T cells and predicted stronger HIV-specific T lymphocyte responses. In the CD8+ T cell compartment of PSPs, we identified an enrichment of stem-like TCF-1+PD-1+ memory cells, whereas pediatric progressors and viremic adults had a terminally exhausted PD-1+CD39+ population. TCF-1+PD-1+ expression on CD8+ T cells was associated with higher proliferative activity and stronger Gag-specific effector functionality. These data prompted the hypothesis that the proliferative burst potential of stem-like HIV-specific cytotoxic cells could be exploited in therapeutic strategies to boost the antiviral response and facilitate remission in infants who received early ART with a preserved and nonexhausted T cell compartment.

Transcriptomic Signatures of Human Immunodeficiency Virus Post-Treatment Control

Posttreatment controllers (PTCs) are rare HIV-infected individuals who can limit viral rebound after antiretroviral therapy interruption (ATI), but the mechanisms of this remain unclear. To investigate these mechanisms, we quantified various HIV RNA transcripts (via reverse transcription droplet digital PCR [RT-ddPCR]) and cellular transcriptomes (via RNA-seq) in blood cells from PTCs and noncontrollers (NCs) before and two time points after ATI. HIV transcription initiation did not significantly increase after ATI in PTCs or in NCs, whereas completed HIV transcripts increased at early ATI in both groups and multiply-spliced HIV transcripts increased only in NCs. Compared to NCs, PTCs showed lower levels of HIV DNA, more cell-associated HIV transcripts per total RNA at all times, no increase in multiply-spliced HIV RNA at early or late ATI, and a reduction in the ratio of completed/elongated HIV RNA after early ATI. NCs expressed higher levels of the IL-7 pathway before ATI and expressed higher levels of multiple cytokine, inflammation, HIV transcription, and cell death pathways after ATI. Compared to the baseline, the NCs upregulated interferon and cytokine (especially TNF) pathways during early and late ATI, whereas PTCs upregulated interferon and p53 pathways only at early ATI and downregulated gene translation during early and late ATI. In NCs, viral rebound after ATI is associated with increases in HIV transcriptional completion and splicing, rather than initiation. Differences in HIV and cellular transcription may contribute to posttreatment control, including an early limitation of spliced HIV RNA, a delayed reduction in completed HIV transcripts, and the differential expression of the IL-7, p53, and TNF pathways. IMPORTANCE The findings presented here provide new insights into how HIV and cellular gene expression change after stopping ART in both noncontrollers and posttreatment controllers. Posttreatment control is associated with an early ability to limit increases in multiply-spliced HIV RNA, a delayed (and presumably immune-mediated) ability to reverse an initial rise in processive/completed HIV transcripts, and multiple differences in cellular gene expression pathways. These differences may represent correlates or mechanisms of posttreatment control and may provide insight into the development and/or monitoring of therapeutic strategies that are aimed at a functional HIV cure.

A More Comprehensive Clinical and Laboratory Characterization of 61 Acute HIV Infection Patients in Southwest China

Acute HIV infection (AHI), i.e., the early stage of HIV infection, plays an important role in immune system failure and HIV transmission, but most AHI patients are missed due to their non-specific symptoms. To facilitate the identification of patients with high AHI risk and reduction of missed diagnosis, we characterized 61 AHI patients in a Southwest China hospital with 4300 beds; specifically, we characterized their general clinical characteristics, evolution in results of a novel HIV screening assay called Elecsys^® HIV Duo, and by programming, we analyzed the ability of all routine laboratory tests (e.g., routine blood analysis) to identify AHI patients. Among 61 AHI patients, 85.2% were male and the median age was 42 (interquartile range, 25-62) years. A total of 61.9% of patients visit the emergency department first during AHI. Clinical presentation of AHI patients included fever, fatigue, chills, rash, and various respiratory, digestive, and nervous system symptoms. Two of three results from Elecsys^® HIV Duo show clear evolution trends: HIV P24 antigen decreased while HIV antibody increased in consecutive samples of nearly all patients. High fluorescence lymphocytes have a very high positive likelihood ratio (LR+) of 10.33 and a relatively high "rate of out-of-range tests" of 56.8% (21 in 37 patients who received this test had a result outside the reference range). In addition, we identified more than ten tests with LR+ greater than two. In summary, the emergency department is important for AHI screening. The evolution of HIV P24 Ag and HIV Ab and those laboratory tests with a high "rate of out-of-range tests" or high LR+ may aid the AHI identification and missed diagnosis reduction.

Progressive transformation of the HIV-1 reservoir cell profile over two decades of antiviral therapy

HIV-1 establishes a life-long reservoir of virally infected cells which cannot be eliminated by antiretroviral therapy (ART). Here, we demonstrate a markedly altered viral reservoir profile of long-term ART-treated individuals, characterized by large clones of intact proviruses preferentially integrated in heterochromatin locations, most prominently in centromeric satellite/micro-satellite DNA. Longitudinal evaluations suggested that this specific reservoir configuration results from selection processes that promote the persistence of intact proviruses in repressive chromatin positions, while proviruses in permissive chromosomal locations are more likely to be eliminated. A bias toward chromosomal integration sites in heterochromatin locations was also observed for intact proviruses in study participants who maintained viral control after discontinuation of antiretroviral therapy. Together, these results raise the possibility that antiviral selection mechanisms during long-term ART may induce an HIV-1 reservoir structure with features of deep latency and, possibly, more limited abilities to drive rebound viremia upon treatment interruptions.

The Many Faces of Immune Activation in HIV-1 Infection: A Multifactorial Interconnection

Chronic immune activation has a significant role in HIV-1 disease pathogenesis and CD4+ T-cell depletion. The causes of chronic inflammation and immune activation are incompletely understood, but they are likely multifactorial in nature, involving both direct and indirect stimuli. Possible explanations include microbial translocation, coinfection, and continued presence of competent replicating virus. In fact, long-term viral suppression treatments are unable to normalize elevated markers of systemic immune activation. Furthermore, high levels of pro-inflammatory cytokines increase susceptibility to premature aging of the immune system. The phenomenon of "inflammaging" has begun to be evident in the last decades, as a consequence of increased life expectancy due to the introduction of cART. Quality of life and survival have improved substantially; however, PLWH are predisposed to chronic inflammatory conditions leading to age-associated diseases, such as inflammatory bowel disease, neurocognitive disorders, cardiovascular diseases, metabolic syndrome, bone abnormalities, and non-HIV-associated cancers. Several approaches have been studied in numerous uncontrolled and/or randomized clinical trials with the aim of reducing immune activation/inflammatory status in PLWH, none of which have achieved consistent results.

New insights into transcription elongation control of HIV-1 latency and rebound

Antiretroviral therapy reduces circulating HIV-1 to undetectable amounts but does not eliminate the virus due to the persistence of a stable reservoir of latently infected cells. The reservoir is maintained both by proliferation of latently infected cells and by reseeding from reactivated cells. A major challenge for the field is to find safe and effective methods to eliminate this source of rebounding HIV-1. Studies on the molecular mechanisms leading to HIV-1 latency and reactivation are being transformed using latency models in primary and patient CD4⁺ T cells. These studies have revealed the central role played by the biogenesis of the transcription elongation factor P-TEFb (Positive Transcription Elongation Factor b) and its recruitment to proviral HIV-1, for the maintenance of viral latency and the control of viral reactivation.

Frailty and Aging in HIV- Status Post 13 Years of National Awareness

The People aged 50 years and above comprise over 50% of people living with HIV (PLWH) in the US. Despite the advances made with anti-retroviral therapy in increasing their life span, PLWH are plagued with non-AIDS associated conditions which increase their risk for morbidity and mortality. Frailty, a decline in physical and functional reserve, is one of the manifestations of aging, has a prevalence of 5-30%, and occurs up to 2 decades earlier in people aging with HIV (PAWH). The majority of providers for PAWH have minimal experience with the concept of gerontology, frailty, and aging. Hence, there is a gap in clinicians' knowledge on how to address frailty and aging in PAWH. This review will focus on the clinical interventions that mitigate frailty and aging in PAWH as well as highlight areas of investigation towards achieving these mediations. Beyond the identification of the roles of exercise and nutrition, more studies are needed on the pragmatic approach to apply these resources to routine care. There should be continued reinforcement of the proven strategy of combination antiretroviral therapy as well as treatment of co-infections and age-appropriate health and cancer screening in PAWH.

Bibliometric and visualized analysis of elite controllers based on CiteSpace: landscapes, hotspots, and frontiers

Background

A unique subset of people living with HIV, known as elite controllers, possess spontaneous and consistent control over viral replication and disease progression in the absence of antiviral intervention. In-depth research on elite controllers is conducive to designing better treatment strategies for HIV. However, comprehensive and illuminating bibliometric reports on elite controllers are rare.

Methods

Articles on elite controllers were retrieved from the Web of Science Core Collection. A visualized analysis of this domain was conducted by CiteSpace software. Taking count, betweenness centrality, and burst value as criteria, we interpreted the visualization results and predicted future new directions and emerging trends.

Results

By December 31, 2022, 843 articles related to elite controllers had been published. The largest contributors in terms of country, institution, and author were the United States (485), Univ Calif San Francisco (87), and Walker B.D. (65), respectively. Migueles S.A. (325) and Journal of Virology (770) were the most cocited author and journal, respectively. Additionally, by summarizing the results of our CiteSpace software analysis on references and keywords, we considered that the research hotspots and frontiers on elite controllers mainly focus on three aspects: deciphering the mechanisms of durable control, delineating the implications for the development of treatments for HIV infection, and highlighting the clinical risks faced by elite controllers and coping strategies.

Conclusion

This study performed a bibliometric and visual analysis of elite controllers, identified the main characteristics and emerging trends, and provided insightful references for further development of this rapidly evolving and complex field.

Immunological and virological findings in a patient with exceptional post-treatment control: a case report

BACKGROUND

Although antiretroviral therapy (ART) is effective in suppressing viral replication, HIV-1 persists in reservoirs and rebounds after ART has been stopped. However, a very few people (eg, elite and post-treatment controllers) are able to maintain viral loads below detection limits without ART, constituting a realistic model for long-term HIV remission. Here, we describe the HIV control mechanisms of an individual who showed exceptional post-treatment control for longer than 15 years.

METHODS

We report the case of a Hispanic woman aged 59 years with sexually acquired acute HIV infection, who was included in an immune-mediated primary HIV infection trial involving a short course of ciclosporine A, interleukin-2, granulocyte macrophage colony-stimulating factor, and pegylated interferon alfa, followed by analytical treatment interruption. We did the following viral assays: total and integrated HIV-1 DNA in CD4 T cells and rectal tissue, quantitative viral outgrowth assay, HIV-1 infectivity in peripheral blood mononuclear cells and CD4 T-cell cultures and viral inhibitory activity by natural killer (NK) and CD8 T cells. NK and T-cell phenotypes were determined by flow cytometry. HLA, killer cell immunoglobulin-like receptors, Δ32CCR5, and NKG2C alleles were genotyped.

FINDINGS

After ART and immunomodulatory treatment, the person maintained undetectable plasma viral load for 15 years. HIV-1 subtype was CFR_02AG, CCR5-tropic. We found progressive reductions in viral reservoir during the 15-year treatment interruption: total HIV DNA (from 4573·50 copies per 10⁶ CD4 T cells to 95·33 copies per 10⁶ CD4 T cells) and integrated DNA (from 85·37 copies per 10⁶ CD4 T cells to 5·25 copies per 10⁶ CD4 T cells). Viral inhibition assays showed strong inhibition of in vitro HIV replication in co-cultures of CD4 T cells with autologous NK or CD8 T cells at 1:2 ratio (75% and 62%, respectively). Co-cultures with NK and CD8 T cells resulted in 93% inhibition. We detected higher-than-reference levels of both NKG2C-memory-like NK cells (46·2%) and NKG2C γδ T cells (64·9%) associated with HIV-1 control.

INTERPRETATION

We described long-term remission in a woman aged 59 years who was treated during primary HIV infection and has maintained undetectable viral load for 15 years without ART. Replication-competent HIV-1 was isolated. NKG2C-memory-like NK cells and γδ T cells were associated with the control viral replication. Strategies promoting these cells could bring about long-term HIV remission.

FUNDING

Fondo Europeo para el Desarrollo Regional (FEDER), SPANISH AIDS Research Network (RIS), Fondo de Investigación Sanitaria (FIS), HIVACAT, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), CERCA Programme/Generalitat de Catalunya, la Caixa Foundation, and Centro de Investigación Biomédica en Red de Enfermedades Infecciosas (CIBERINFEC).

TRANSLATION

For the Spanish translation of the abstract see Supplementary Materials section.

Genotypic Resistance Testing of HIV-1 DNA in Peripheral Blood Mononuclear Cells

HIV-1 DNA exists in nonintegrated linear and circular episomal forms and as integrated proviruses. In patients with plasma viremia, most peripheral blood mononuclear cell (PBMC) HIV-1 DNA consists of recently produced nonintegrated virus DNA while in patients with prolonged virological suppression (VS) on antiretroviral therapy (ART), most PBMC HIV-1 DNA consists of proviral DNA produced months to years earlier. Drug-resistance mutations (DRMs) in PBMCs are more likely to coexist with ancestral wild-type virus populations than they are in plasma, explaining why next-generation sequencing is particularly useful for the detection of PBMC-associated DRMs. In patients with ongoing high levels of active virus replication, the DRMs detected in PBMCs and in plasma are usually highly concordant. However, in patients with lower levels of virus replication, it may take several months for plasma virus DRMs to reach detectable levels in PBMCs. This time lag explains why, in patients with VS, PBMC genotypic resistance testing (GRT) is less sensitive than historical plasma virus GRT, if previous episodes of virological failure and emergent DRMs were either not prolonged or not associated with high levels of plasma viremia. Despite the increasing use of PBMC GRT in patients with VS, few studies have examined the predictive value of DRMs on the response to a simplified ART regimen. In this review, we summarize what is known about PBMC HIV-1 DNA dynamics, particularly in patients with suppressed plasma viremia, the methods used for PBMC HIV-1 GRT, and the scenarios in which PBMC GRT has been used clinically.

Advances in Pediatric HIV-1 Cure Therapies and Reservoir Assays

Significant advances in the field of HIV-1 therapeutics to achieve antiretroviral treatment (ART)-free remission and cure for persons living with HIV-1 are being made with the advent of broadly neutralizing antibodies and very early ART in perinatal infection. The need for HIV-1 remission and cure arises due to the inability of ART to eradicate the major reservoir for HIV-1 in resting memory CD4+ T cells (the latent reservoir), and the strict adherence to lifelong treatment. To measure the efficacy of these cure interventions on reservoir size and to dissect reservoir dynamics, assays that are sensitive and specific to intact proviruses are critical. In this review, we provided a broad overview of some of the key interventions underway to purge the reservoir in adults living with HIV-1 and ones under study in pediatric populations to reduce and control the latent reservoir, primarily focusing on very early treatment in combination with broadly neutralizing antibodies. We also summarized assays currently in use to measure HIV-1 reservoirs and their feasibility and considerations for studies in children.

Challenges of HIV therapeutic vaccines clinical trials design

PURPOSE OF THE REVIEW

To discuss main challenges of therapeutic vaccine clinical trials design, implementation and analyses in the HIV cure field.

RECENT FINDINGS

Therapeutic vaccines are progressively being postulated as T-cell stimulating agents to use in combination HIV cure strategies, with the addition of immunomodulators, latency reversing agents and/or broadly neutralizing antibodies. Although promising strategies are rapidly evolving in preclinical studies using nonhuman primate models, translation into human testing in randomized controlled clinical trials is more challenging and expensive to conduct. Adaptive designs, access to cohorts of early-treated individuals, consensus on how to safely conduct analytical treatment interruptions, use of alternative statistical methods, development of point-of-care/home-based testing technologies and ensuring early engagement of communities where research is being developed are some of the critical aspects to consider to facilitate clinical trial development in the HIV cure field.

SUMMARY

Design and development of HIV therapeutic vaccine clinical trials poses many challenges, from Phase 0/pilot studies to Phase I/II trials in which efficacy of the intervention is being tested and antiretroviral therapy cessation is needed, complexity of cure trials progressively increases. Understanding fundamental issues and careful planning of therapeutic vaccine clinical trials is crucial to minimize design flaws, reduce loss of follow-ups and missing data while ensuring participant's safety and guarantee valid and accurate analyses and thus, better contribute towards an HIV cure.

Current strategies to induce selective killing of HIV-1-infected cells

Although combination antiretroviral therapy (ART) has led to significant HIV-1 suppression and improvement in immune function, persistent viral reservoirs remain that are refractory to intensified ART. ART poses many challenges such as adherence to drug regimens, the emergence of resistant virus, and cumulative toxicity resulting from long-term therapy. Moreover, latent HIV-1 reservoir cells can be stochastically activated to produce viral particles despite effective ART and contribute to the rapid viral rebound that typically occurs within 2 weeks of ART interruption; thus, lifelong ART is required for continued viral suppression. Several strategies have been proposed to address the HIV-1 reservoir such as reactivation of HIV-1 transcription using latency reactivating agents with a combination of ART, host immune clearance and HIV-1-cytotoxicity to purge the infected cells-a "shock and kill" strategy. However, these approaches do not take into account the multiple transcriptional and translational blocks that contribute to HIV-1 latency or the complex heterogeneity of the HIV-1 reservoir, and clinical trials have thus far failed to produce the desired results. Here, we describe alternative strategies being pursued that are designed to kill selectively HIV-1-infected cells while sparing uninfected cells in the absence of enhanced humoral or adaptive immune responses.

Long-term antiretroviral therapy initiated in acute HIV infection prevents residual dysfunction of HIV-specific CD8+ T cells

Background

Harnessing CD8⁺ T cell responses is being explored to achieve HIV remission. Although HIV-specific CD8⁺ T cells become dysfunctional without treatment, antiretroviral therapy (ART) partially restores their function. However, the extent of this recovery under long-term ART is less understood.

Methods

We analyzed the differentiation status and function of HIV-specific CD8⁺ T cells after long-term ART initiated in acute or chronic HIV infection ex vivo and upon in vitro recall.

Findings

ART initiation in any stage of acute HIV infection promoted the persistence of long-lived HIV-specific CD8⁺ T cells with high expansion (P<0·0008) and cytotoxic capacity (P=0·02) after in vitro recall, albeit at low cell number (P=0·003). This superior expansion capacity correlated with stemness (r=0·90, P=0·006), measured by TCF-1 expression, similar to functional HIV-specific CD8⁺ T cells found in spontaneous controllers. Importanly, TCF-1 expression in these cells was associated with longer time to viral rebound ranging from 13 to 48 days after ART interruption (r =0·71, P=0·03). In contrast, ART initiation in chronic HIV infection led to more differentiated HIV-specific CD8⁺ T cells lacking stemness properties and exhibiting residual dysfunction upon recall, with reduced proliferation and cytolytic activity.

Interpretation

ART initiation in acute HIV infection preserves functional HIV-specific CD8⁺ T cells, albeit at numbers too low to control viral rebound post-ART. HIV remission strategies may need to boost HIV-specific CD8⁺ T cell numbers and induce stem cell-like properties to reverse the residual dysfunction persisting on ART in people treated after acute infection prior to ART release.

Funding

U.S. National Institutes of Health and U.S. Department of Defense.

Sex differences in HIV-1 persistence and the implications for a cure

Of the 38 million people currently living with Human Immunodeficiency Virus type-1 (HIV-1), women, especially adolescents and young women, are disproportionally affected by the HIV-1 pandemic. Acquired immunodeficiency syndrome (AIDS) - related illnesses are the leading cause of death in women of reproductive age worldwide. Although combination antiretroviral therapy (cART) can suppress viral replication, cART is not curative due to the presence of a long-lived viral reservoir that persists despite treatment. Biological sex influences the characteristics of the viral reservoir as well as the immune responses to infection, factors that can have a significant impact on the design and quantification of HIV-1 curative interventions in which women are grossly underrepresented. This mini-review will provide an update on the current understanding of the impact of biological sex on the viral reservoir and will discuss the implications of these differences in the context of the development of potential HIV-1 curative strategies, with a focus on the shock and kill approach to an HIV-1 cure. This mini-review will also highlight the current gaps in the knowledge of sex-based differences in HIV-1 persistence and will speculate on approaches to address them to promote the development of more scalable, effective curative approaches for people living with HIV-1.

Acute HIV-1 infection viremia associate with rebound upon treatment interruption

BACKGROUND

Analytic treatment interruption (ATI) studies evaluate strategies to potentially induce remission in people living with HIV-1 but are often limited in sample size. We combined data from four studies that tested three interventions (vorinostat/hydroxychloroquine/maraviroc before ATI, Ad26/MVA vaccination before ATI, and VRC01 antibody infusion during ATI).

METHODS

The statistical validity of combining data from these participants was evaluated. Eleven variables, including HIV-1 viral load at diagnosis, Fiebig stage, and CD4+ T cell count were evaluated using pairwise correlations, statistical tests, and Cox survival models.

FINDINGS

Participants had homogeneous demographic and clinical characteristics. Because an antiviral effect was seen in participants who received VRC01 infusion post-ATI, these participants were excluded from the analysis, permitting a pooled analysis of 53 participants. Time to viral rebound was significantly associated with variables measured at the beginning of infection: pre-antiretroviral therapy (ART) viral load (HR = 1.34, p = 0.022), time to viral suppression post-ART initiation (HR = 1.07, p < 0.001), and area under the viral load curve (HR = 1.34, p = 0.026).

CONCLUSIONS

We show that higher viral loads in acute HIV-1 infection were associated with faster viral rebound, demonstrating that the initial stage of HIV-1 infection before ART initiation has a strong impact on viral rebound post-ATI years later.

FUNDING

This work was supported by a cooperative agreement between the Henry M. Jackson Foundation for the Advancement of Military Medicine and the US Department of the Army (W81XWH-18-2-0040). This research was funded, in part, by the US National Institute of Allergy and Infectious Diseases (AAI20052001) and the I4C Martin Delaney Collaboratory (5UM1AI126603-05).

Contribution of the HIV-1 Envelope Glycoprotein to AIDS Pathogenesis and Clinical Progression

In the absence of antiviral therapy, HIV-1 infection progresses to a wide spectrum of clinical manifestations that are the result of an entangled contribution of host, immune and viral factors. The contribution of these factors is not completely established. Several investigations have described the involvement of the immune system in the viral control. In addition, distinct HLA-B alleles, HLA-B27, -B57-58, were associated with infection control. The combination of these elements and antiviral host restriction factors results in different clinical outcomes. The role of the viral proteins in HIV-1 infection has been, however, less investigated. We will review contributions dedicated to the pathogenesis of HIV-1 infection focusing on studies identifying the function of the viral envelope glycoprotein (Env) in the clinical progression because of its essential role in the initial events of the virus life-cycle. Some analysis showed that inefficient viral Envs were dominant in non-progressor individuals. These poorly-functional viral proteins resulted in lower cellular activation, viral replication and minor viral loads. This limited viral antigenic production allows a better immune response and a lower immune exhaustion. Thus, the properties of HIV-1 Env are significant in the clinical outcome of the HIV-1 infection and AIDS pathogenesis.

CD8 + T-cell responses in HIV controllers: potential implications for novel HIV remission strategies

PURPOSE OF REVIEW

Immunological studies of spontaneous HIV and simian virus (SIV) controllers have identified virus-specific CD8 +  T cells as a key immune mechanism of viral control. The purpose of this review is to consider how knowledge about the mechanisms that are associated with CD8 +  T cell control of HIV/SIV in natural infection can be harnessed in HIV remission strategies.

RECENT FINDINGS

We discuss characteristics of CD8 +  T-cell responses that may be critical for suppressing HIV replication in spontaneous controllers comprising HIV antigen recognition including specific human leukocyte antigen types, broadly cross-reactive T cell receptors and epitope targeting, enhanced expansion and antiviral functions, and localization of virus-specific T cells near sites of reservoir persistence. We also discuss the need to better understand the timing of CD8 +  T-cell responses associated with viral control of HIV/SIV during acute infection and after treatment interruption as well as the mechanisms by which HIV/SIV-specific CD8 +  T cells coordinate with other immune responses to achieve control.

SUMMARY

We propose implications as to how this knowledge from natural infection can be applied in the design and evaluation of CD8 +  T-cell-based remission strategies and offer questions to consider as these strategies target distinct CD8 +  T-cell-dependent mechanisms of viral control.

Towards a molecular profile of antiretroviral therapy-free HIV remission

PURPOSE OF REVIEW

To summarize the current status and highlight recent findings on predictive biomarkers for posttreatment HIV control (PTC) and virological remission. While historically, many studies focused on virological markers, there is an increasing tendency to enter immune and metabolic factors into the equation.

RECENT FINDINGS

On the virological side, several groups reported that cell-associated HIV RNA could predict time to viral rebound. Recent data hints at the possible importance of the genic location and chromatin context of the integrated provirus, although these factors still need to be assessed in relation to PTC and virological remission. Evidence from immunological studies highlighted innate and humoral immunity as important factors for prolonged HIV remission. Interestingly, novel metabolic markers have emerged, which offer additional angles to our understanding of latency and viral rebound.

SUMMARY

Facilitating PTC and virological remission remain top priorities for the HIV cure research. We advocate for clear and precise definitions for both phenomena in order to avoid misconceptions and to strengthen the conclusions that can be drawn. As no one-size-fits-all marker has emerged yet, more biomarkers are on the horizon, and viral rebound is a complex and heterogeneous process, it is likely that a combination of various biomarkers in cohesion will be necessary for a more accurate prediction of antiretroviral therapy-free HIV remission.

Elite and posttreatment controllers, two facets of HIV control

PURPOSE OF REVIEW

The quest for HIV-1 cure could take advantage of the study of rare individuals that control viral replication spontaneously (elite controllers) or after an initial course of antiretroviral therapy (posttreatment controllers, PTCs). In this review, we will compare back-to-back the immunological and virological features underlying viral suppression in elite controllers and PTCs, and explore their possible contributions to the HIV-1 cure research.

RECENT FINDINGS

HIV-1 control in elite controllers shows hallmarks of an effective antiviral response, favored by genetic background and possibly associated to residual immune activation. The immune pressure in elite controllers might select against actively transcribing intact proviruses, allowing the persistence of a small and poorly inducible reservoir. Evidence on PTCs is less abundant but preliminary data suggest that antiviral immune responses may be less pronounced. Therefore, these patients may rely on distinct mechanisms, not completely elucidated to date, suppressing HIV-1 transcription and replication.

SUMMARY

PTCs and elite controllers may control HIV replication using distinct pathways, the elucidation of which may contribute to design future interventional strategies aiming to achieve a functional cure.

Impact of antiretroviral therapy in primary HIV infection on natural killer cell function and the association with viral rebound and HIV DNA following treatment interruption

Natural Killer (NK) cells play a key role in controlling HIV replication, with potential downstream impact on the size of the HIV reservoir and likelihood of viral rebound after antiretroviral therapy (ART) cessation. It is therefore important to understand how primary HIV infection (PHI) disrupts NK cell function, and how these functions are restored by early ART. We examined the impact of commencing ART during PHI on phenotypic and functional NK cell markers at treatment initiation (baseline), 3 months, 1 year, and 2 years in seven well-characterised participants in comparison to HIV seronegative volunteers. We then examined how those NK cell properties differentially impacted by ART related to time to viral rebound and HIV DNA levels in 44 individuals from the SPARTAC trial who stopped ART after 48 weeks treatment, started during PHI. NK cell markers that were significantly different between the seven people with HIV (PWH) treated for 2 years and HIV uninfected individuals included NKG2C levels in CD56dim NK cells, Tim-3 expression in CD56bright NK cells, IFN-γ expressed by CD56dim NK cells after IL-12/IL-18 stimulation and the fraction of Eomes-/T-bet+ in CD56dim and CD56bright NK cells. When exploring time to viral rebound after stopping ART among the 44 SPARTAC participants, no single NK phenotypic marker correlated with control. Higher levels of IL-12/IL-18 mediated NK cell degranulation at baseline were associated with longer times to viral rebound after treatment interruption (P=0.028). Additionally, we found higher fractions of CD56dim NK cells in individuals with lower levels of HIV DNA (P=0.048). NKG2A and NKp30 levels in CD56neg NK cells were higher in patients with lower HIV DNA levels (p=0.00174, r=-0.49 and p=0.03, r= -0.327, respectively) while CD27 levels were higher in those with higher levels of HIV DNA (p=0.026). These data show NK cell functions are heterogeneously impacted by HIV infection with a mixed picture of resolution on ART, and that while NK cells may affect HIV DNA levels and time to viral rebound, no single NK cell marker defined delayed viral rebound.

The HIV Latency Reversal Agent HODHBt Enhances NK Cell Effector and Memory-Like Functions by Increasing Interleukin-15-Mediated STAT Activation

Elimination of human immunodeficiency virus (HIV) reservoirs is a critical endpoint to eradicate HIV. One therapeutic intervention against latent HIV is "shock and kill." This strategy is based on the transcriptional activation of latent HIV with a latency-reversing agent (LRA) with the consequent killing of the reactivated cell by either the cytopathic effect of HIV or the immune system. We have previously found that the small molecule 3-hydroxy-1,2,3-benzotriazin-4(3H)-one (HODHBt) acts as an LRA by increasing signal transducer and activator of transcription (STAT) factor activation mediated by interleukin-15 (IL-15) in cells isolated from aviremic participants. The IL-15 superagonist N-803 is currently under clinical investigation to eliminate latent reservoirs. IL-15 and N-803 share similar mechanisms of action by promoting the activation of STATs and have shown some promise in preclinical models directed toward HIV eradication. In this work, we evaluated the ability of HODHBt to enhance IL-15 signaling in natural killer (NK) cells and the biological consequences associated with increased STAT activation in NK cell effector and memory-like functions. We showed that HODHBt increased IL-15-mediated STAT phosphorylation in NK cells, resulting in increases in the secretion of CXCL-10 and interferon gamma (IFN-γ) and the expression of cytotoxic proteins, including granzyme B, granzyme A, perforin, granulysin, FASL, and TRAIL. This increased cytotoxic profile results in increased cytotoxicity against HIV-infected cells and different tumor cell lines. HODHBt also improved the generation of cytokine-induced memory-like NK cells. Overall, our data demonstrate that enhancing the magnitude of IL-15 signaling with HODHBt favors NK cell cytotoxicity and memory-like generation, and thus, targeting this pathway could be further explored for HIV cure interventions. IMPORTANCE Several clinical trials targeting the HIV latent reservoir with LRAs have been completed. In spite of a lack of clinical benefit, they have been crucial to elucidate hurdles that "shock and kill" strategies have to overcome to promote an effective reduction of the latent reservoir to lead to a cure. These hurdles include low reactivation potential mediated by LRAs, the negative influence of some LRAs on the activity of natural killer and effector CD8 T cells, an increased resistance to apoptosis of latently infected cells, and an exhausted immune system due to chronic inflammation. To that end, finding therapeutic strategies that can overcome some of these challenges could improve the outcome of shock and kill strategies aimed at HIV eradication. Here, we show that the LRA HODHBt also improves IL-15-mediated NK cell effector and memory-like functions. As such, pharmacological enhancement of IL-15-mediated STAT activation can open new therapeutic avenues toward an HIV cure.

Altered T-cell subset distribution in the viral reservoir in HIV-1-infected individuals with extremely low proviral DNA (LoViReTs)

BACKGROUND

HIV cure strategies aim to eliminate viral reservoirs that persist despite successful antiretroviral therapy (ART). We have previously described that 9% of HIV-infected individuals who receive ART harbor low levels of provirus (LoViReTs).

METHODS

We selected 22 LoViReTs matched with 22 controls ART suppressed for more than 3 years with fewer than 100 and more than 100 HIV-DNA copies/10⁶  CD4⁺ T cells, respectively. We measured HIV reservoirs in blood and host genetic factors. Fourteen LoViReTs underwent leukapheresis to analyze replication-competent virus, and HIV-DNA in CD4⁺ T-cell subpopulations. Additionally, we measured HIV-DNA in rectum and/or lymph node biopsies from nine of them.

RESULTS

We found that LoViReTs harbored not only lower levels of total HIV-DNA, but also significantly lower intact HIV-DNA, cell-associated HIV-RNA, and ultrasensitive viral load than controls. The proportion of intact versus total proviruses was similar in both groups. We found no differences in the percentage of host factors. In peripheral blood, 71% of LoViReTs had undetectable replication-competent virus. Minimum levels of total HIV-DNA were found in rectal and lymph node biopsies compared with HIV-infected individuals receiving ART. The main contributors to the reservoir were short-lived transitional memory and effector memory T cells (47% and 29%, respectively), indicating an altered distribution of the HIV reservoir in the peripheral T-cell subpopulations of LoViReTs.

CONCLUSION

In conclusion, LoViReTs are characterized by low levels of viral reservoir in peripheral blood and secondary lymphoid tissues, which might be explained by an altered distribution of the proviral HIV-DNA towards more short-lived memory T cells. LoViReTs can be considered exceptional candidates for future interventions aimed at curing HIV.

CD8 lymphocytes mitigate HIV-1 persistence in lymph node follicular helper T cells during hyperacute-treated infection

HIV persistence in tissue sites despite ART is a major barrier to HIV cure. Detailed studies of HIV-infected cells and immune responses in native lymph node tissue environment is critical for gaining insight into immune mechanisms impacting HIV persistence and clearance in tissue sanctuary sites. We compared HIV persistence and HIV-specific T cell responses in lymph node biopsies obtained from 14 individuals who initiated therapy in Fiebig stages I/II, 5 persons treated in Fiebig stages III-V and 17 late treated individuals who initiated ART in Fiebig VI and beyond. Using multicolor immunofluorescence staining and in situ hybridization, we detect HIV RNA and/or protein in 12 of 14 Fiebig I/II treated persons on suppressive therapy for 1 to 55 months, and in late treated persons with persistent antigens. CXCR3+ T follicular helper cells harbor the greatest amounts of gag mRNA transcripts. Notably, HIV-specific CD8+ T cells responses are associated with lower HIV antigen burden, suggesting that these responses may contribute to HIV suppression in lymph nodes during therapy. These results reveal HIV persistence despite the initiation of ART in hyperacute infection and highlight the contribution of virus-specific responses to HIV suppression in tissue sanctuaries during suppressive ART.

HIV cure strategies: which ones are appropriate for Africa?

Although combination antiretroviral therapy (ART) has reduced mortality and improved lifespan for people living with HIV, it does not provide a cure. Patients must be on ART for the rest of their lives and contend with side effects, unsustainable costs, and the development of drug resistance. A cure for HIV is, therefore, warranted to avoid the limitations of the current therapy and restore full health. However, this cure is difficult to find due to the persistence of latently infected HIV cellular reservoirs during suppressive ART. Approaches to HIV cure being investigated include boosting the host immune system, genetic approaches to disable co-receptors and the viral genome, purging cells harboring latent HIV with latency-reversing latency agents (LRAs) (shock and kill), intensifying ART as a cure, preventing replication of latent proviruses (block and lock) and boosting T cell turnover to reduce HIV-1 reservoirs (rinse and replace). Since most people living with HIV are in Africa, methods being developed for a cure must be amenable to clinical trials and deployment on the continent. This review discusses the current approaches to HIV cure and comments on their appropriateness for Africa.

Genotypic and Phenotypic Diversity of the Replication-Competent HIV Reservoir in Treated Patients

In HIV infection, viral rebound after treatment discontinuation is considered to originate predominantly from viral genomes integrated in resting CD4⁺ T lymphocytes. Replication-competent proviral genomes represent a minority of the total HIV DNA. While the quantification of the HIV reservoir has been extensively studied, the diversity of genomes that compose the reservoir was less explored. Here, we measured the genotypic and phenotypic diversity in eight patients with different treatment histories. Between 4 and 14 (mean, 8) individual viral isolates per patient were obtained using a virus outgrowth assay, and their near-full-length genomes were sequenced. The mean pairwise distance (MPD) observed in different patients correlated with the time before undetectable viremia was achieved (r = 0.864, P = 0.0194), suggesting that the complexity of the replication-competent reservoir mirrors that present at treatment initiation. No correlation was instead observed between MPD and the duration of successful treatment (mean, 8 years; range, 2 to 21 years). For 5 of the 8 patients, genotypically identical viral isolates were observed in independent wells, suggesting clonal expansion of infected cells. Identical viruses represented between 25 and 60% of the isolates (mean, 48%). The proportion of identical viral isolates correlated with the duration of treatment (r = 0.822, P = 0.0190), suggesting progressive clonal expansion of infected cells during ART. A broader range of infectivity was also observed among isolates from patients with delayed viremia control (r = 0.79, P = 0.025). This work unveiled differences in the genotypic and phenotypic features of the replication-competent reservoir from treated patients and suggests that delaying treatment results in increased diversity of the reservoir.

IMPORTANCE In HIV-infected and effectively treated individuals, integrated proviral genomes may persist for decades. The vast majority of the genomes, however, are defective, and only the replication-competent fraction represents a threat of viral reemergence. The quantification of the reservoir has been thoroughly explored, while the diversity of the genomes has been insufficiently studied. Its characterization, however, is relevant for the design of strategies aiming the reduction of the reservoir. Here, we explored the replication-competent near-full-length HIV genomes of eight patients who experienced differences in the delay before viremia control and in treatment duration. We found that delayed effective treatment was associated with increased genetic diversity of the reservoir. The duration of treatment did not impact the diversity but was associated with higher frequency of clonally expanded sequences. Thus, early treatment initiation has the double advantage of reducing both the size and the diversity of the reservoir.

Approach to the management of paediatric HIV spontaneous controllers

Paediatric HIV spontaneous controllers (HSCs) are a unique and understudied population with potential to inform alternative treatment options for patients living with HIV. As HSCs are so rare and often not recognised prior to antiretroviral treatment (ART) initiation, it can be difficult for clinicians to optimally manage this group. We describe the diagnosis, history and management of three paediatric HSCs, two girls and a boy who were followed for 2, 1.25 and 10.4 years, respectively, before starting ART. All had low but detectable viral loads throughout follow-up but mostly marginally low CD4:CD8 ratios. The reason for starting ART in all was a gradual tendency to poorer virological control. This case series should assist in recognising paediatric HSCs. Clinical dilemmas arising in the management of paediatric HSCs include arriving at a correct HIV-positive diagnosis, correct diagnosis as an HSC, as well as whether to initiate ART. Decision-making for initiation of ART in paediatric HSCs should be individualised. Factors supporting ART initiation in these patients included increased frequency of viral load blips, increasing detectable viral load, CD4 percentage and CD4:CD8 ratio. Other factors included Hepatitis C serology and highly sensitive C-reactive protein. All three patients ultimately required ART, which supports universal initiation of ART in paediatric HSCs, but further research is required.

Significance of initiating antiretroviral therapy in the early stage of HIV infection

A growing number of guidelines now recommend that human immunodeficiency virus (HIV) infected patients should be given early antiretroviral therapy (ART), especially in acute HIV infection. ART during early infection can limit viral reservoirs and improve immune cell function. From a societal prospect, early-infected individuals who achieve a state of viral suppression through ART can reduce the chance of HIV transmission and reduce the acquired immunodeficiency syndrome (AIDS)-related disease burden. However, there are many problems in the early diagnosis and treatment of HIV infection, including personal and social factors, which hinder the implementation and development of early treatment. It is recommended that initiating ART in the early stage of HIV infection, combined with other treatment strategies, so as to achieve functional cure.

Changes to the Simian Immunodeficiency Virus (SIV) Reservoir and Enhanced SIV-Specific Responses in a Rhesus Macaque Model of Functional Cure after Serial Rounds of Romidepsin Administrations

HIV persistence requires lifelong antiretroviral therapy (ART), calling for a cure. The histone deacetylase inhibitor, romidepsin, is used in the "shock and kill" approach with the goal of reactivating virus and subsequently clearing infected cells through cell-mediated immune responses. We tested serial and double infusions of romidepsin in a rhesus macaque (RM) model of SIV functional cure, which controls virus without ART. Off ART, romidepsin reactivated SIV in all RMs. Subsequent infusions resulted in diminished reactivation, and two RMs did not reactivate the virus after the second or third infusions. Therefore, those two RMs received CD8-depleting antibody to assess the replication competence of the residual reservoir. The remaining RMs received double infusions, i.e., two doses separated by 48-h. Double infusions were well tolerated, induced immune activation, and effectively reactivated SIV. Although reactivation was gradually diminished, cell-associated viral DNA was minimally changed, and viral outgrowth occurred in 4/5 RMs. In the RM which did not reactivate after CD8 depletion, viral outgrowth was not detected in peripheral blood mononuclear cells (PBMC)-derived CD4+ cells. The frequency of SIV-specific CD8+ T cells increased after romidepsin administration, and the increased SIV-specific immune responses were associated, although not statistically, with the diminished reactivation. Thus, our data showing sequential decreases in viral reactivation with repeated romidepsin administrations with all RMs and absence of viral reactivation after CD8+ T-cell depletion in one animal suggest that, in the context of healthy immune responses, romidepsin affected the inducible viral reservoir and gradually increased immune-mediated viral control. Given the disparities between the results of romidepsin administration to ART-suppressed SIVmac239-infected RMs and HIV-infected normal progressors compared to our immune-healthy model, our data suggest that improving immune function for greater SIV-specific responses should be the starting point of HIV cure strategies. IMPORTANCE HIV cure is sought after due to the prevalence of comorbidities that occur in persons with HIV. One of the most investigated HIV cure strategies is the "shock and kill" approach. Our study investigated the use of romidepsin, a histone deacetylase (HDAC) inhibitor, in our rhesus macaque model of functional cure, which allows for better resolution of viral reactivation due to the lack of antiretroviral therapy. We found that repeated rounds of romidepsin resulted in gradually diminished viral reactivation. One animal inevitably lacked replication-competent virus in the blood. With the accompanying enhancement of the SIV-specific immune response, our data suggest that there is a reduction of the viral reservoir in one animal by the cell-mediated immune response. With the differences observed between our model and persons living with HIV (PWH) treated with romidepsin, specifically in the context of a healthy immune system in our model, our data thereby indicate the importance of restoring the immune system for cure strategies.

Single-Cell Imaging Shows That the Transcriptional State of the HIV-1 Provirus and Its Reactivation Potential Depend on the Integration Site

Current antiretroviral treatment fails to cure HIV-1 infection since latent provirus resides in long-lived cellular reservoirs, rebounding whenever therapy is discontinued. The molecular mechanisms underlying HIV-1 latency are complex where the possible link between integration and transcription is poorly understood. HIV-1 integration is targeted toward active chromatin by the direct interaction with a host protein, lens epithelium-derived growth factor (LEDGF/p75). LEDGINs are small-molecule inhibitors of the LEDGF/p75-integrase (IN) interaction that effectively inhibit and retarget HIV-1 integration out of preferred integration sites, resulting in residual provirus that is more latent. Here, we describe a single-cell branched DNA imaging method for simultaneous detection of viral DNA and RNA. We investigated how treatment with LEDGINs affects the location, transcription, and reactivation of HIV-1 in both cell lines and primary cells. This approach demonstrated that LEDGIN-mediated retargeting hampered the baseline transcriptional state and the transcriptional reactivation of the provirus, evidenced by the reduction in viral RNA expression per residual copy. Moreover, treatment of primary cells with LEDGINs induced an enrichment of provirus in deep latency. These results corroborate the impact of integration site selection for the HIV-1 transcriptional state and support block-and-lock functional cure strategies in which the latent reservoir is permanently silenced after retargeting.

Insights into the HIV-1 Latent Reservoir and Strategies to Cure HIV-1 Infection

Since the first discovery of human immunodeficiency virus 1 (HIV-1) in 1983, the targeted treatment, antiretroviral therapy (ART), has effectively limited the detected plasma viremia below a very low level and the technique has been improved rapidly. However, due to the persistence of the latent reservoir of replication-competent HIV-1 in patients treated with ART, a sudden withdrawal of the drug inevitably results in HIV viral rebound and HIV progression. Therefore, more understanding of the HIV-1 latent reservoir (LR) is the priority before developing a cure that thoroughly eliminates the reservoir. HIV-1 spreads through both the release of cell-free particles and by cell-to-cell transmission. Mounting evidence indicates that cell-to-cell transmission is more efficient than cell-free transmission of particles and likely influences the pathogenesis of HIV-1 infection. This mode of viral transmission also influences the generation and maintenance of the latent reservoir, which represents the main obstacle for curing the infection. In this review, the definition, establishment, and maintenance of the HIV-1 LR, along with the state-of-the-art quantitative approaches that directly quantify HIV-1 intact proviruses, are elucidated. Strategies to cure HIV infection are highlighted. This review will renew hope for a better and more thorough cure of HIV infection for mankind and encourage more clinical trials to achieve ART-free HIV remission.

Antiretroviral therapy duration and immunometabolic state determine efficacy of ex vivo dendritic cell-based treatment restoring functional HIV-specific CD8+ T cells in people living with HIV

Background

Dysfunction of CD8⁺ T cells in people living with HIV-1 (PLWH) receiving anti-retroviral therapy (ART) has restricted the efficacy of dendritic cell (DC)-based immunotherapies against HIV-1. Heterogeneous immune exhaustion and metabolic states of CD8⁺ T cells might differentially associate with dysfunction. However, specific parameters associated to functional restoration of CD8⁺ T cells after DC treatment have not been investigated.

Methods

We studied association of restoration of functional HIV-1-specific CD8⁺ T cell responses after stimulation with Gag-adjuvant-primed DC with ART duration, exhaustion, metabolic and memory cell subsets profiles.

Findings

HIV-1-specific CD8⁺ T cell responses from a larger proportion of PLWH on long-term ART (more than 10 years; LT-ARTp) improved polyfunctionality and capacity to eliminate autologous p24⁺ infected CD4⁺ T cells in vitro. In contrast, functional improvement of CD8⁺ T cells from PLWH on short-term ART (less than a decade; ST-ARTp) after DC treatment was limited. This was associated with lower frequencies of central memory CD8⁺ T cells, increased co-expression of PD1 and TIGIT and reduced mitochondrial respiration and glycolysis induction upon TCR activation. In contrast, CD8⁺ T cells from LT-ARTp showed increased frequencies of TIM3⁺ PD1⁻ cells and preserved induction of glycolysis. Treatment of dysfunctional CD8⁺ T cells from ST-ARTp with combined anti-PD1 and anti-TIGIT antibodies plus a glycolysis promoting drug restored their ability to eliminate infected CD4⁺ T cells.

Interpretation

Together, our study identifies specific immunometabolic parameters for different PLWH subgroups potentially useful for future personalized DC-based HIV-1 vaccines.

Funding

NIH (R21AI140930), MINECO/FEDER RETOS (RTI2018-097485-A-I00) and CIBERINF grants.

Viral and Host Biomarkers of HIV Remission Post Treatment Interruption

PURPOSE OF REVIEW

HIV rebound/remission after antiretroviral therapy (ART) interruption is likely influenced by (a) the size of the inducible replication-competent HIV reservoir and (b) factors in the host environment that influence immunological pressures on this reservoir. Identifying viral and/or host biomarkers of HIV rebound after ART cessation may improve the safety of treatment interruptions and our understanding of how the viral-host interplay results in post-treatment control. Here we review the predictive and functional significance of recently suggested viral and host biomarkers of time to viral rebound and post-treatment control following ART interruption.

RECENT FINDINGS

There are currently no validated viral or host biomarkers of viral rebound; however, several biomarkers have been recently suggested. A combination of viral and host factors will likely be needed to predict viral rebound and to better understand the mechanisms contributing to post-treatment control of HIV, critical steps to developing a cure for HIV infection.

Natural Killer Cells in Antibody Independent and Antibody Dependent HIV Control

Infection with the human immunodeficiency virus (HIV), when left untreated, typically leads to disease progression towards acquired immunodeficiency syndrome. Some people living with HIV (PLWH) control their virus to levels below the limit of detection of standard viral load assays, without treatment. As such, they represent examples of a functional HIV cure. These individuals, called Elite Controllers (ECs), are rare, making up <1% of PLWH. Genome wide association studies mapped genes in the major histocompatibility complex (MHC) class I region as important in HIV control. ECs have potent virus specific CD8⁺ T cell responses often restricted by protective MHC class I antigens. Natural Killer (NK) cells are innate immune cells whose activation state depends on the integration of activating and inhibitory signals arising from cell surface receptors interacting with their ligands on neighboring cells. Inhibitory NK cell receptors also use a subset of MHC class I antigens as ligands. This interaction educates NK cells, priming them to respond to HIV infected cell with reduced MHC class I antigen expression levels. NK cells can also be activated through the crosslinking of the activating NK cell receptor, CD16, which binds the fragment crystallizable portion of immunoglobulin G. This mode of activation confers NK cells with specificity to HIV infected cells when the antigen binding portion of CD16 bound immunoglobulin G recognizes HIV Envelope on infected cells. Here, we review the role of NK cells in antibody independent and antibody dependent HIV control.

Role of Early Life Cytotoxic T Lymphocyte and Natural Killer Cell Immunity in Paediatric HIV Cure/Remission in the Anti-Retroviral Therapy Era

Only three well-characterised cases of functional cure have been described in paediatric HIV infection over the past decade. This underlines the fact that early initiation of combination antiretroviral therapy (cART), whilst minimising the size of the viral reservoir, is insufficient to achieve cure, unless other factors contribute. In this review, we consider these additional factors that may facilitate functional cure in paediatric infection. Among the early life immune activity, these include HIV-specific cytotoxic T-lymphocyte (CTL) and natural killer (NK) cell responses. The former have less potent antiviral efficacy in paediatric compared with adult infection, and indeed, in early life, NK responses have greater impact in suppressing viral replication than CTL. This fact may contribute to a greater potential for functional cure to be achieved in paediatric versus adult infection, since post-treatment control in adults is associated less with highly potent CTL activity, and more with effective antiviral NK cell responses. Nonetheless, antiviral CTL responses can play an increasingly effective role through childhood, especially in individuals expressing then 'protective' HLA-I molecules HLA-B*27/57/58:01/8101. The role of the innate system on preventing infection, in shaping the particular viruses transmitted, and influencing outcome is discussed. The susceptibility of female fetuses to in utero mother-to-child transmission, especially in the setting of recent maternal infection, is a curiosity that also provides clues to mechanisms by which cure may be achieved, since initial findings are that viral rebound is less frequent among males who interrupt cART. The potential of broadly neutralising antibody therapy to facilitate cure in children who have received early cART is discussed. Finally, we draw attention to the impact of the changing face of the paediatric HIV epidemic on cure potential. The effect of cART is not limited to preventing AIDS and reducing the risk of transmission. cART also affects which mothers transmit. No longer are mothers who transmit those who carry genes associated with poor immune control of HIV. In the cART era, a high proportion (>70% in our South African study) of transmitting mothers are those who seroconvert in pregnancy or who for social reasons are diagnosed late in pregnancy. As a result, now, genes associated with poor immune control of HIV are not enriched in mothers who transmit HIV to their child. These changes will likely influence the effectiveness of HLA-associated immune responses and therefore cure potential among children.

Isotopic Radiolabeling of the Antiretroviral Drug [18F]Dolutegravir for Pharmacokinetic PET Imaging

Deciphering the drug/virus/host interactions at infected cell reservoirs is a key leading to HIV-1 remission for which positron emission tomography (PET) imaging using radiolabeled antiretroviral (ARV) drugs is a powerful asset. Dolutegravir (DTG) is one of the preferred therapeutic options to treat HIV and can be isotopically labeled with fluorine-18. [18F]DTG was synthesized via a three-step approach of radiofluorination/nitrile reduction/peptide coupling with optimization for each step. Radiofluorination was performed on 2-fluoro-4-nitrobenzonitrile in 90% conversion followed by nitrile reduction using sodium borohydride and aqueous nickel(II) chloride with 72% conversion. Final peptide coupling reaction followed by HPLC purification and formulation afforded ready-to-inject [18F]DTG in 5.1 ± 0.8% (n = 10) decay-corrected radiochemical yield within 95 min. The whole process was automatized using a TRACERlab® FX NPro module, and quality control performed by analytical HPLC showed that [18F]DTG was suitable for in vivo injection with >99% chemical and radiochemical purity and a molar activity of 83 ± 18 GBq/µmol (n = 10). Whole-body distribution of [18F]DTG was performed by PET imaging on a healthy macaque and highlighted the elimination routes of the tracer. This study demonstrated the feasibility of in vivo [18F]DTG PET imaging and paved the way to explore drug/virus/tissues interactions in animals and humans.

Evolving Strategies to Eliminate the CD4 T Cells HIV Viral Reservoir via CAR T Cell Immunotherapy

Although the advent of ART has significantly reduced the morbidity and mortality associated with HIV infection, the stable pool of HIV in latently infected cells requires lifelong treatment adherence, with the cessation of ART resulting in rapid reactivation of the virus and productive HIV infection. Therefore, these few cells containing replication-competent HIV, known as the latent HIV reservoir, act as the main barrier to immune clearance and HIV cure. While several strategies involving HIV silencing or its reactivation in latently infected cells for elimination by immune responses have been explored, exciting cell based immune therapies involving genetically engineered T cells expressing synthetic chimeric receptors (CAR T cells) are highly appealing and promising. CAR T cells, in contrast to endogenous cytotoxic T cells, can function independently of MHC to target HIV-infected cells, are efficacious and have demonstrated acceptable safety profiles and long-term persistence in peripheral blood. In this review, we present a comprehensive picture of the current efforts to target the HIV latent reservoir, with a focus on CAR T cell therapies. We highlight the current challenges and advances in this field, while discussing the importance of novel CAR designs in the efforts to find a HIV cure.

Influence of Combination Antiretroviral Therapy on HIV-1 Serological Responses and Their Implications: A Systematic Review and Meta-Analysis

We aimed to analyze HIV-1 seroreversion caused by combination antiretroviral therapy (cART) and to explore antibody levels of anti-HIV-1 as an alternative biomarker of HIV-1 reservoir. We searched PubMed, Embase, the Cochrane Library, and Web of Science up to August 2021 for publications about the performance of HIV-1 serological assays or the association between antibody responses against HIV-1 and HIV-1 reservoirs. Potential sources of heterogeneity were explored by meta-regression analysis, including the year of publication, country, pretreatment viral load, sample size, the timing of treatment, time on cART, and principle or type of serological assay. Twenty-eight eligible studies with a total population of 1,883 were included in the meta-analysis. The pooled frequency of HIV-1 seronegativity is 38.0% (95% CI: 28.0%–49.0%) among children with vertical HIV-1 infection and cART initiation at the age of less than 6 months, while the percentage of HIV-1 seronegativity declined to 1.0% (95% CI: 0%–3.0%) when cART was initiated at the age of >6 months. For adult patients, 16.0% (95% CI: 9.0%–24.0%) of them were serologically negative when cART was initiated at acute/early infection of HIV-1, but the seronegative reaction was rarely detected when cART was started at chronic HIV-1 infection. Substantial heterogeneity was observed among the studies to estimate the frequency of HIV-1 seronegativity in the early-cART population (I² ≥ 70%, p < 0.05 and all), while mild heterogeneity existed for the deferred-cART subjects. Moreover, anti-HIV-1 antibody response positively correlates with HIV-1 reservoir size with a pooled rho of 0.43 (95% CI: 0.28–0.55), suggesting that anti-HIV antibody level may be a feasible biomarker of HIV-1 reservoir size.