Circulating immune and plasma biomarkers of time to HIV rebound in HIV controllers treated with vesatolimod.

Background: Antiretroviral therapy (ART) for HIV-1 treatment has improved lifespan but requires lifelong adherence for people living with HIV (PLWH), highlighting the need for a cure. Evaluation of potential cure strategies requires analytic treatment interruption (ATI) with close monitoring of viral rebound. Predictive biomarkers for HIV-1 rebound and/or duration of control during ATI will facilitate these HIV cure trials while minimizing risks. Available evidence suggests that host immune, glycomic, lipid, and metabolic markers of inflammation may be associated with HIV-1 persistence in PLWH who are treated during chronic HIV-1 infection. Methods: We conducted post-hoc analysis of HIV controllers who could maintain low levels of plasma HIV-1 without ART in a phase 1b vesatolimod trial. Baseline and pre-ATI levels of immune, glycomic, lipidomic, and metabolomic markers were tested for association with ATI outcomes (time of HIV-1 rebound to 200 copies/mL and 1,000 copies/mL, duration of HIV-1 RNA ≤400 copies/mL and change in intact proviral HIV-1 DNA during ATI) using Spearman's correlation and Cox proportional hazards model. Results: Higher levels of CD69+CD8+ T-cells were consistently associated with shorter time to HIV-1 rebound at baseline and pre-ATI. With few exceptions, baseline fucosylated, non-galactosylated, non-sialylated, bisecting IgG N-glycans were associated with shorter time to HIV rebound and duration of control as with previous studies. Baseline plasma MPA and HPA binding glycans and non-galactosylated/non-sialylated glycans were associated with longer time to HIV rebound, while baseline multiply-galactosylated glycans and sialylated glycans, GNA-binding glycans, NPA-binding glycans, WGA-binding glycans, and bisecting GlcNAc glycans were associated with shorter time to HIV rebound and duration of control. Fourteen bioactive lipids had significant baseline associations with longer time to rebound and duration of control, and larger intact proviral HIV-1 DNA changes; additionally, three baseline bioactive lipids were associated with shorter time to first rebound and duration of control. Conclusion: Consistent with studies in HIV non-controllers, proinflammatory glycans, lipids, and metabolites were generally associated with shorter duration of HIV-1 control. Notable differences were observed between HIV controllers vs. non-controllers in some specific markers. For the first time, exploratory biomarkers of ATI viral outcomes in HIV-controllers were investigated but require further validation.

Mosaic vaccine-induced antibody-dependent cellular phagocytosis associated with delayed HIV-1 viral load rebound post treatment interruption.

A heterologous Ad26/MVA vaccine was given prior to an analytic treatment interruption (ATI) in people living with HIV-1 (mainly CRF01_AE) who initiated antiretroviral treatment (ART) during acute HIV-1. We investigate the impact of Ad26/MVA vaccination on antibody (Ab)-mediated immune responses and their effect on time to viral rebound. The vaccine mainly triggers vaccine-matched binding Abs while, upon viral rebound post ATI, infection-specific CRF01_AE binding Abs increase in all participants. Binding Abs are not associated with time to viral rebound. The Ad26/MVA mosaic vaccine profile consists of correlated non-CRF01_AE binding Ab and Fc effector features, with strong Ab-dependent cellular phagocytosis (ADCP) responses. CRF01_AE-specific ADCP responses (measured either prior to or post ATI) are significantly higher in individuals with delayed viral rebound. Our results suggest that vaccines eliciting cross-reactive responses with circulating viruses in a target population could be beneficial and that ADCP responses may play a role in viral control post treatment interruption.

HIV remission trial investigators' attitudes towards risk and risk mitigation in trials that include treatment interruption.

Early-phase HIV remission ("cure") trials aim to test interventions developed to eradicate HIV or to sustainably control HIV without antiretroviral treatment (ART). Many remission trials include analytic treatment interruption (ATI) to evaluate interventions, which increases the risk to participants and their sexual partners. We conducted an online questionnaire of international HIV remission trial investigators and other study team members to assess their expectations regarding the time to achieve long-term control of HIV replication without treatment (functional cure) or complete eradication of replication-competent HIV virus (sterilizing cure); attitudes toward HIV remission research and the feasibility, acceptability, and efficacy of six HIV transmission risk mitigation strategies during trials with ATI of fixed duration. Nearly half of respondents (47%) reported expecting a functional cure for HIV to be achieved in 5-10 years, and one-third (35%) reported 10-20 years for a sterilizing cure to be achieved. On a scale of -3 to 3, mean scores indicated greater respondent concern about the risk of HIV transmission to partners during ATI (Time to rebound Mean: 0.4 and Fixed duration Mean: 11), compared to participant health risks from ATI (Time to Rebound Mean: -.9 and Fixed duration Mean: 0.0). With regard to feasibility, acceptability, and efficacy respectively, mitigation efforts rated positively included: requiring counseling for potential participants (Means: 2.3; 2.1; and 1.1), providing partner referrals for PrEP (Means: 1.3; 1.3; 1.5), providing pre-exposure proxylaxis directly to partners (Means: 1.0; 1.5; 1.6), and monitoring participants for new sexually transmitted disease acquisition (Means: 1.9; 1.4; 1.0). Respondents were less positive about requiring that participants' sexual partner(s) participate in risk counseling or limiting participation to those who commit to abstaining from sex during the entire ATI period. Our study demonstrates that HIV remission trial investigators and study team members are concerned about the risk of transmission to sexual partners during ATI. Separating the assessment of risk mitigation strategies for transmission risk into feasibility, acceptability, and efficacy allows the discovery of strategies that may best achieve all three outcomes. Additional research is needed to compare these more fine-grained assessments with views held by other investigators, people living with HIV, and trial participants.

The Essential Need for Trust When Transmission Risk Cannot Be Eliminated in HIV-Remission Trials.

Analytic treatment interruption (ATI) is scientifically necessary in HIV-remission ("cure") studies to test the effects of new interventions. However, stopping antiretroviral treatment poses risks to research participants and their sexual partners. Ethical debate about whether and how to conduct such studies has largely centered on designing risk-mitigation strategies and identifying the responsibilities of research stakeholders. In this paper, we argue that because the possibility of HIV transmission from research participants to partners during ATI cannot practicably be eliminated-that is, it is ineliminable-the successful conduct of such trials ultimately depends on relationships of trust and trustworthiness. We describe our experiences with conducting and studying HIV-remission trials with ATI in Thailand to examine the strengths, complexities, and limitations of the risk-mitigation and responsibility approaches and to explore ways in which the building of trust-and trustworthiness-may help enhance the scientific, practical, and ethical dimensions of these trials.

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.

The ethical case for placebo control in HIV-cure-related studies with ART interruption.

Many studies that seek to cure HIV must ask participants to interrupt their antiretroviral treatment. In such circumstances, is it permissible to include a placebo group in the study? We explain why doing so is a scientific and an ethical necessity, and more benign than imagined.

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).

Attitudes About Analytic Treatment Interruption (ATI) in HIV Remission Trials with Different Antiretroviral Therapy (ART) Resumption Criteria.

HIV remission trials often require temporary stopping of antiretroviral therapy (ART)-an approach called analytic treatment interruption (ATI). Trial designs resulting in viremia raise risks for participants and sexual partners. We conducted a survey on attitudes about remission trials, comparing ART resumption criteria (lower-risk "time to rebound" and higher-risk "sustained viremia") among participants from an acute HIV cohort in Thailand. Analyses included Wilcoxon-Ranks and multivariate logistic analysis. Most of 408 respondents supported ATI trials, with slightly higher approval of, and willingness to participate in, trials using time to rebound versus sustained viremia criteria. Less than half of respondents anticipated disclosing trial participation to partners and over half indicated uncertainty or unwillingness about whether partners would be willing to use PrEP. Willingness to participate was higher among those who rated higher trial approval, lower anticipated burden, and those expecting to make the decision independently. Our findings support acceptability of ATI trials among most respondents. Participant attitudes and anticipated behaviors, especially related to transmission risk, have implications for future trial design and informed consent.

Central Nervous System Safety During Brief Analytic Treatment Interruption of Antiretroviral Therapy Within 4 Human Immunodeficiency Virus Remission Trials: An Observational Study in Acutely Treated People Living With Human Immunodeficiency Virus.

BACKGROUND: The central nervous system (CNS) is a likely reservoir of human immunodeficiency virus (HIV), vulnerable to viral rebound, inflammation, and clinical changes upon stopping antiretroviral therapy (ART). It is critical to evaluate the CNS safety of studies using analytic treatment interruption (ATI) to assess HIV remission. METHODS: Thirty participants who started ART during acute HIV infection underwent CNS assessments across 4 ATI remission trials. ART resumption occurred with plasma viral load >1000 copies/mL. CNS measures included paired pre- vs post-ATI measures of mood, cognitive performance, and neurologic examination, with elective cerebrospinal fluid (CSF) sampling, brain diffusion tensor imaging (DTI) and magnetic resonance spectroscopy (MRS). RESULTS: Median participant age was 30 years old and 29/30 were male. Participants' median time on ART before ATI was 3 years, and ATI lasted a median of 35 days. Post-ATI, there were no differences in median mood scores or neurologic findings and cognitive performance improved modestly. During ATI, a low level of CSF HIV-1 RNA was detectable in 6 of 20 participants with plasma viremia, with no group changes in CSF immune activation markers or brain DTI measures. Mild worsening was identified in post-ATI basal ganglia total choline MRS, suggesting an alteration in neuronal membranes. CONCLUSION: No adverse CNS effects were observed with brief, closely monitored ATI in participants with acutely treated HIV, except an MRS alteration in basal ganglia choline. Further studies are needed to assess CNS ATI safety in HIV remission trials, particularly for studies using higher thresholds to restart ART and longer ATI durations.

Initiation of Antiretroviral Therapy during Primary HIV Infection: Effects on the Latent HIV Reservoir, Including on Analytic Treatment Interruptions.

Antiretroviral therapy (ART) inhibits HIV replication but does not eradicate the latent reservoir. The previous research suggests that earlier ART initiation provides benefit on limiting reservoir size, but timing and extent of this effect remain unclear. Analytic treatment interruption (ATI) may be used to demonstrate HIV remission, but whether early ART also improves likelihood or duration of even temporary virologic remission is unclear. This review seeks to answer both questions. We performed a systematic review and analysis following Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines and included 21 interventional or observational studies with sufficient HIV reservoir outcomes. We also aggregated reservoir outcomes and transformed data into approximate measurements of total HIV DNA per million peripheral blood mononuclear cells and analyzed the correlation between timing of ART initiation and reservoir size. People living with HIV who initiate ART in primary infection maintain smaller reservoirs on suppressive ART than those who initiate treatment during chronic infection. The reduction of reservoir is most pronounced when ART is started within 2 weeks of HIV acquisition. Across studies, we found a moderately strong association between longer time to ART initiation and reservoir size, which was strongest when measured after 1 year on ART (Pearson's r = 0.69, p = 0.0003). After ATI, larger pre-ATI reservoir size predicts shorter time to viral rebound. Early ART may also facilitate long-term control of viremia. Although achieving sustained HIV remission will require further interventions, initiating ART very early in infection could limit the extent of the reservoir and also lead to post-ATI control in rare cases.

Virologic and Immunologic Features of Simian Immunodeficiency Virus Control Post-ART Interruption in Rhesus Macaques.

Antiretroviral therapy (ART) cannot eradicate human immunodeficiency virus (HIV) and a rapid rebound of virus replication follows analytical treatment interruption (ATI) in the vast majority of HIV-infected individuals. Sustained control of HIV replication without ART has been documented in a subset of individuals, defined as posttreatment controllers (PTCs). The key determinants of post-ART viral control remain largely unclear. Here, we identified 7 SIVmac239-infected rhesus macaques (RMs), defined as PTCs, who started ART 8 weeks postinfection, continued ART for >7 months, and controlled plasma viremia at <104 copies/ml for up to 8 months after ATI and <200 copies/ml at the latest time point. We characterized immunologic and virologic features associated with post-ART SIV control in blood, lymph node (LN), and colorectal (RB) biopsy samples compared to 15 noncontroller (NC) RMs. Before ART initiation, PTCs had higher CD4 T cell counts, lower plasma viremia, and SIV-DNA content in blood and LN compared to NCs, but had similar CD8 T cell function. While levels of intestinal CD4 T cells were similar, PTCs had higher frequencies of Th17 cells. On ART, PTCs had significantly lower levels of residual plasma viremia and SIV-DNA content in blood and tissues. After ATI, SIV-DNA content rapidly increased in NCs, while it remained stable or even decreased in PTCs. Finally, PTCs showed immunologic benefits of viral control after ATI, including higher CD4 T cell levels and reduced immune activation. Overall, lower plasma viremia, reduced cell-associated SIV-DNA, and preserved Th17 homeostasis, including at pre-ART, are the main features associated with sustained viral control after ATI in SIV-infected RMs.IMPORTANCE While effective, antiretroviral therapy is not a cure for HIV infection. Therefore, there is great interest in achieving viral remission in the absence of antiretroviral therapy. Posttreatment controllers represent a small subset of individuals who are able to control HIV after cessation of antiretroviral therapy, but characteristics associated with these individuals have been largely limited to peripheral blood analysis. Here, we identified 7 SIV-infected rhesus macaques that mirrored the human posttreatment controller phenotype and performed immunologic and virologic analysis of blood, lymph node, and colorectal biopsy samples to further understand the characteristics that distinguish them from noncontrollers. Lower viral burden and preservation of immune homeostasis, including intestinal Th17 cells, both before and after ART, were shown to be two major factors associated with the ability to achieve posttreatment control. Overall, these results move the field further toward understanding of important characteristics of viral control in the absence of antiretroviral therapy.

Risk to Nonparticipants in HIV Remission Studies With Treatment Interruption: A Symposium.

Ethical guidelines and recommendations for human subjects research typically focus on protecting the individuals who directly participate in that research. However, additional people, including sex partners of research participants, can also face harms and burdens from medical studies. In human immunodeficiency virus (HIV) cure-related research, a persistent ethical and practical challenge surrounds the use of analytical antiretroviral treatment interruptions. The challenge is usually discussed in relation to risks to study participants, but serious dangers accrue to nonparticipants, including sex partners of study participants. This multidisciplinary supplement relays the risks for nonparticipating sex partners in HIV cure-related studies and addresses the ethical dilemmas raised by these studies, with recommendations for researchers, advocates, sponsors, and oversight bodies.

Is it ethical to isolate study participants to prevent HIV transmission during trials with an analytical treatment interruption?

This commentary considers an extreme idea for protecting against human immunodeficiency virus (HIV) transmission to sex partners of individuals participating in HIV remission studies with an analytical treatment interruption (ATI). Other human challenge studies, such as studies of influenza, commonly isolate participants during the trial, to protect their contacts and the community against infection. Why should HIV studies with a treatment interruption be any different, one might wonder? This article concludes that isolation should not be used in HIV remission studies with an ATI but also shows that the matter is complex.

Human Immunodeficiency Virus Transmission Risk in Analytical Treatment Interruption Studies: Relational Factors and Moral Responsibility.

Analytical treatment interruption (ATI) is becoming common in human immunodeficiency virus (HIV) cure-related research, but its use is controversial. ATI raises concerns about risks of HIV transmission to sexual partners of study participants. Researchers may have difficulty addressing these risks, given that study participants' private behavior is implicated, the partners are not enrolled in the research, and behavioral HIV risk mitigation strategies usually fall outside the study objectives. This analysis argues that researchers should assume some responsibility for partners' risks, based on the importance of partner relationships for the study participants themselves, and out of concern for the partners' welfare. Adding this responsibility is reasonable since the risk is created in part by research procedures, and since concern for third parties is often part of professional standards for healthcare providers. Study participants and their partners also bear some responsibility. Specific recommendations for measures to address risk are discussed.

Removing One Barrier to Protecting Sex Partners in HIV Remission Studies With a Treatment Interruption.

Only a few of the recommendations made in this supplement are implemented in ongoing HIV remission studies that involve an analytical treatment interruption. The absence of these recommendations in protocols puts sexual partners of study participants at serious risk. This paper addresses one possible barrier to implementation: a certain misunderstanding among sponsors and research entities.

How to Address the Risk of HIV Transmission in Remission Studies With Treatment Interruption: The Low-Hanging Fruit Approach.

Some HIV remission studies include a treatment interruption that seriously risks infecting participants' sex partners with HIV. What, ethically, is owed to these nonparticipants? Until greater certainty emerges on what protections should be afforded nonparticipants of research studies, what I call a "low-hanging fruit" approach may help researchers and review bodies determine how to address infection risks to nonparticipants in these studies.

Going off antiretroviral treatment in a closely monitored HIV "cure" trial: longitudinal assessments of acutely diagnosed trial participants and decliners.

INTRODUCTION: The South East Asia Research Collaboration in HIV (SEARCH) RV411 clinical trial in Thailand was a systematic investigation of analytic treatment interruption (ATI) in individuals diagnosed and treated since Fiebig stage I acute HIV infection. Here, we explore decision-making processes and perceptions of trial participation in a phase I trial that raised important ethical considerations, to identify potential areas of improvement in this relatively new field of HIV research. Similar considerations apply to other HIV phase I trials, especially those involving ATI, making this trial a model to identify challenges and opportunities in promoting informed choice. METHODS: Using longitudinal semi-structured interviews and a validated questionnaire, we examined how decisions to join or decline the trial were made, whether there was evidence of decisional conflict, and reactions to the trial outcomes. We also explored contrasting views and experiences in this small trial cohort. We report analyses of data from these questionnaires and interviews, conducted from February through December of 2016 with the 14 SEARCH cohort participants who either joined (n = 8) or declined (n = 6) participation in RV411. RESULTS: The eight participants and six decliners had low overall decisional conflict, which remained low over time. Decision making was more difficult for decliners than participants, at least initially. While all interviewees described being satisfied with their decisions, our study identified important negative consequences for a few individuals, including seroconversion, negative experiences with optional procedures and disappointment due to rapid viral rebound. CONCLUSIONS: Although our results reflect the experiences of a small group invited to join this trial, our overall finding of low decisional conflict even while some individuals reported negative experiences provides lessons for clinical trial investigators. We developed points-to-consider in helping participants make informed choices, to support participants during the trial and to support decliners in their decisions.

Unintended HIV-1 Transmission to a Sex Partner in a Study of a Therapeutic Vaccine Candidate.

We report a case of sexual transmission of human immunodeficiency virus (HIV) that occurred during treatment discontinuation in a therapeutic vaccine trial, following oral sex. Transmission occurred even though the index participant was an HIV/AIDS activist, particularly well informed about the risks and modalities of transmission. This case report highlights the risk of secondary transmission of HIV during cessation of treatment in HIV cure-related trials.

Immunogenicity of AGS-004 Dendritic Cell Therapy in Patients Treated During Acute HIV Infection.

AGS-004 consists of matured autologous dendritic cells co-electroporated with in vitro transcribed RNA encoding autologous HIV antigens. In an open-label, single arm sub-study of AGS-004-003, AGS-004 was administered monthly to suppressed participants who started antiretroviral therapy (ART) during acute HIV infection. HIV-1 specific T cell responses were measured by multicolor flow cytometry after 3-4 doses. The frequency of resting CD4+ T-cell infection (RCI) was measured by quantitative viral outgrowth assay. Participants demonstrating increased immune response postvaccination were eligible for analytic treatment interruption (ATI). AGS-004 induced a positive immune response defined as ≥2-fold increase from baseline in the number of multifunctional HIV-1 specific CD28+/CD45RA- CD8+ effector/memory cytoxic T-lymphocytes (CTLs) in all six participants. All participants underwent ATI with rebound viremia at a median of 29 days. Immune correlates between time to viral rebound and the induction of effector CTLs were determined. Baseline RCI was low in most participants (0.043-0.767 IUPM). One participant had a >2-fold decrease (0.179-0.067 infectious units per million [IUPM]) in RCI at week 10. One participant with the lowest RCI had the longest ATI. AGS-004 dendritic cell administration increased multifunctional HIV-specific CD28+/CD45RA- CD8+ memory T cell responses in all participants, but did not permit sustained ART interruption. However, greater expansion of CD28-/CCR7-/CD45RA- CD8+ effector T cell responses correlated with a longer time to viral rebound. AGS-004 may be a useful tool to augment immune responses in the setting of latency reversal and eradication strategies.

Impact of HLA Class I Alleles on Timing of HIV Rebound After Antiretroviral Treatment Interruption.

BACKGROUND: Identifying host determinants associated with HIV reservoir size and timing of viral rebound after an analytic treatment interruption (ATI) is an important step in the search for an HIV functional cure. We performed a pooled analysis of 103 participants from 4 AIDS Clinical Trials Group ATI studies to identify the association between HLA class I alleles with HIV reservoir size and viral rebound timing. METHODS: Total HIV DNA and cell-associated HIV RNA (CA-RNA) were quantified in pre-ATI peripheral blood mononuclear cell samples, and residual plasma viremia was measured using the single-copy assay. HLA class I typing was performed, and we generated an odds ratio (OR) of predicted HLA effect on HIV viremia control for each individual and compared this with time to viral rebound, and levels of HIV DNA and CA-RNA. RESULTS: There was no significant association between the HLA ORs and levels of HIV DNA or CA-RNA, but carriage of protective HLA-B alleles (lower OR scores) was associated with delayed viral rebound (P = 0.02). Higher OR scores at the HLA-C locus were associated with longer duration of ART treatment (P = 0.02) and this trend was also seen with the combined OR score (P < 0.01). Individuals with protective HLA-B alleles had delayed viral rebound after treatment interruption that was not explained by differences in baseline reservoir size. CONCLUSIONS: The results indicate the vital role of cellular host immunity in preventing HIV rebound and the importance of taking into account the HLA status of study participants being evaluated in trials for an HIV cure.