Long-term effects of early antiretroviral initiation on HIV reservoir markers: a longitudinal analysis of the MERLIN clinical study

Autologous neutralizing antibody responses after antiretroviral therapy in acute and early HIV-1

BACKGROUNDEarly antiretroviral therapy initiation (ARTi) in HIV-1 restricts reservoir size and diversity while preserving immune function, potentially improving opportunities for immunotherapeutic cure strategies. For antibody-based cure approaches, the development of autologous neutralizing antibodies (anAbs) after acute/early ARTi is relevant but is poorly understood.METHODSWe characterized antibody responses in a cohort of 23 participants following ARTi in acute HIV (<60 days after acquisition) and early HIV (60-128 days after acquisition).RESULTSPlasma virus sequences at the time of ARTi revealed evidence of escape from anAbs after early, but not acute, ARTi. HIV-1 envelopes representing the transmitted/founder virus(es) (acute ARTi) or escape variants (early ARTi) were tested for sensitivity to longitudinal plasma IgG. After acute ARTi, no anAb responses developed over months to years of suppressive ART. In 2 of the 3 acute ARTi participants who experienced viremia after ARTi, however, anAbs arose shortly thereafter. After early ARTi, anAbs targeting those early variants developed between 12 and 42 weeks of ART and continued to increase in breadth and potency thereafter.CONCLUSIONResults indicate a threshold of virus replication (~60 days) required to induce anAbs, after which they continue to expand on suppressive ART to better target the range of reservoir variants.TRIAL REGISTRATIONClinicalTrials.gov NCT02656511.FUNDINGNIH grants U01AI169767, R01AI162646, UM1AI164570, UM1AI164560, U19AI096109, K23GM112526, T32AI118684, P30AI045008, P30AI027763, R24AI067039; Gilead Sciences grant INUS2361354; Viiv Healthcare grant A126326.

Measuring Human Immunodeficiency Virus Reservoirs: Do We Need to Choose Between Quantity and Quality?

The persistence of latent viral genomes in people receiving antiretroviral therapy (ART) is the main obstacle to a cure for human immunodeficiency virus (HIV) infection. Viral reservoirs can be defined as cells harboring HIV genomes that have the ability to produce infectious virions. Precise quantification of the cellular reservoirs of HIV is challenging because these cells are rare, heterogeneous, and outnumbered by a larger number of cells carrying defective genomes. In addition, measuring the inducibility of these proviruses requires functional assays and remains technically difficult. The recent development of single-cell and single-viral genome approaches revealed additional layers of complexity: the cell subsets that harbor proviruses are heterogeneous and their ability to be induced is variable. A substantial fraction of intact HIV genomes may be permanently silenced after years of ART, revealing the underappreciated importance of induction assays. As such, a simple approach that would assess simultaneously the genetic intactness and the inducibility of the reservoir is still lacking. In this study, we review recent advances in the development of methods to quantify and characterize persistently infected cells, and we discuss how these findings can inform the design of future assays aimed at measuring the size of the intact and inducible HIV reservoir.

Age at ART initiation and proviral reservoir size in perinatal HIV-1 infection: considerations for ART-free remission

PURPOSE OF REVIEW

Achieving ART-free remission without the need for lifelong antiretroviral treatment (ART) is a new objective in HIV-1 therapeutics. This review comprehensively examines the literature to evaluate whether the age at ART initiation in children with perinatal HIV-1 influences the size and decay of the HIV-1 reservoir. The insights gathered from this review serve to inform the field on the unique dynamics of HIV-1 reservoir size in perinatal HIV-1 infection as a function of age at ART initiation, as well as inform biomarker profiling and timing of ART-free remission strategies for children living with HIV-1 globally.

RECENT FINDINGS

Recent studies demonstrate that initiating very early effective ART in neonates is feasible and limits HIV-1 reservoir size. The clinical relevance of limiting the HIV-1 reservoir size in perinatal infection was recently demonstrated in the Tatelo Study, which investigated a treatment switch from ART to two broadly neutralizing antibodies (bNAbs) in very early treated children. Low proviral reservoir size was associated with sustained virologic control for 24 weeks on bNAbs.

SUMMARY

Immediate and early ART initiation for neonates and infants with perinatal HIV-1 is essential to restricting HIV-1 reservoir size that may enable ART-free remission.

A Canadian Survey of Research on HIV-1 Latency-Where Are We Now and Where Are We Heading?

Worldwide, almost 40 million people are currently living with HIV-1. The implementation of cART inhibits HIV-1 replication and reduces viremia but fails to eliminate HIV-1 from latently infected cells. These cells are considered viral reservoirs from which HIV-1 rebounds if cART is interrupted. Several efforts have been made to identify these cells and their niches. There has been little success in diminishing the pool of latently infected cells, underscoring the urgency to continue efforts to fully understand how HIV-1 establishes and maintains a latent state. Reactivating HIV-1 expression in these cells using latency-reversing agents (LRAs) has been successful, but only in vitro. This review aims to provide a broad view of HIV-1 latency, highlighting Canadian contributions toward these aims. We will summarize the research efforts conducted in Canadian labs to understand the establishment of latently infected cells and how this informs curative strategies, by reviewing how HIV latency is established, which cells are latently infected, what methodologies have been developed to characterize them, how new compounds are discovered and evaluated as potential LRAs, and what clinical trials aim to reverse latency in people living with HIV (PLWH).

The build-up of stock of stable integrated proviruses overtime explains the difficulty in reducing HIV-1 DNA levels when treatment is initiated at the chronic stage of the infection

Background

Understanding factors affecting the size and the evolution of the HIV reservoir is essential for the development of curative strategies. This study aimed to assess the impact of antiretroviral therapy (ART) initiated during primary infection (PHI) vs chronic infection (CHI) on the levels and dynamics of integrated HIV-1 DNA, a biomarker of viral persistence.

Methods

Integrated and total HIV-1-DNA were measured in the blood of 92 patients treated during PHI (early group) and 41 during CHI (deferred group), at diagnosis, ART initiation, and 12-24 months on treatment.

Results

On ART, detectable (>1.78 log10 copies/106 PBMCs) integrated HIV-1 DNA levels were significantly lower in the early vs deferred group (2.99 log10vs 3.29 log10,p = 0.005). The proportion of undetectable integrated HIV-1 DNA tended to be higher in the early group vs deferred group (61 % vs 46 %; p = 0.133).

Conclusion

Treatment initiated at PHI limits the levels of integrated HIV-1 DNA in blood. However, initiating treatment at CHI does not allow reaching such low levels in most patients, probably because the stable proviruses at that stage are present in the less prone to elimination long-lived cells. Thus, early ART could provide an opportunity to preparing for functional cure and eradication strategies.

HIV Infection and 90-Day Stroke Outcomes in Uganda: A Prospective Observational Cohort Study

Background and Objectives

Little is known about the impact of HIV infection on the clinical presentation and outcomes after stroke in the modern antiretroviral therapy (ART) era. We aimed to compare stroke characteristics and outcomes between persons with HIV (PWH) and without HIV (PWOH) presenting with stroke in Uganda.

Methods

We conducted a matched cohort study at Mulago National Referral Hospital and Mbarara Regional Referral Hospital between January 2018 and November 2020. We enrolled consecutive PWH presenting with CT-confirmed acute or subacute stroke (symptom onset ≤14 days) and matched them by sex and stroke type to 2 consecutive available PWOH admitted to the same hospital. We obtained baseline clinical data and followed participants for 90 days from the day of clinical presentation. We compared stroke severity (defined by the NIH stroke scale [NIHSS]) and 90-day all-cause mortality and morbidity (using the modified Rankin Scale [mRS]) by HIV serostatus with and without adjustment for confounders.

Results

We enrolled 105 PWH and 157 PWOH with stroke. PWH were younger (mean [SD] age 49 [14] vs 59 [16] years, p < 0.001), and nearly 80% (82/105) were on ART for a median of 5 years and a median CD4 count of 214 cells/uL (interquartile range 140, 337). Compared with PWOH, PWH presented with a 3-point lower median NIHSS (16 vs 19, p = 0.011), a 20% lower proportion of all-cause mortality at 90 days (p = 0.001), and had less disability at 90 days (median mRS 4 vs 5, p = 0.004). Age and NIHSS-adjusted odds ratio of 90-day all-cause mortality in PWH compared with PWOH was 0.45 (95% CI 0.22-0.96, p = 0.037).

Discussion

In the modern ART era, PWH with acute stroke in Uganda present with modest stroke and are significantly less likely to die within 90 days than PWOH. This potentially reflects the protective effects of ART, enhanced health care access, and their younger age at stroke presentation.

Long-term persistence of transcriptionally active 'defective' HIV-1 proviruses: implications for persistent immune activation during antiretroviral therapy

OBJECTIVES

People with HIV-1 (PWH) on effective antiretroviral therapy (ART) continue to exhibit chronic systemic inflammation, immune activation, and persistent elevations in markers of HIV-1 infection [including HIV-DNA, cell-associated HIV-RNA (CA HIV-RNA), and antibodies to HIV-1 proteins] despite prolonged suppression of plasma HIV-RNA levels less than 50 copies/ml. Here, we investigated the hypothesis that nonreplicating but transcriptionally and translationally competent 'defective' HIV-1 proviruses may be one of drivers of these phenomena.

DESIGN

A combined cohort of 23 viremic and virologically suppressed individuals on ART were studied.

METHODS

HIV-DNA, CA HIV-RNA, western blot score (measure of anti-HIV-1 antibodies as a surrogate for viral protein expression in vivo ), and key biomarkers of inflammation and coagulation (IL-6, hsCRP, TNF-alpha, tissue factor, and D-dimer) were measured in peripheral blood and analyzed using a combined cross-sectional and longitudinal approaches. Sequences of HIV-DNA and CA HIV-RNA obtained via 5'-LTR-to-3'-LTR PCR and single-genome sequencing were also analyzed.

RESULTS

We observed similar long-term persistence of multiple, unique, transcriptionally active 'defective' HIV-1 provirus clones (average: 11 years., range: 4-20 years) and antibody responses against HIV-1 viral proteins among all ART-treated participants evaluated. A direct correlation was observed between the magnitude of HIV-1 western blot score and the levels of transcription of 'defective' HIV-1 proviruses ( r  = 0.73, P  < 0.01). Additional correlations were noted between total CD8 + T-cell counts and HIV-DNA ( r  = 0.52, P  = 0.01) or CA HIV-RNA ( r  = 0.65, P  < 0.01).

CONCLUSION

These findings suggest a novel interplay between transcription and translation of 'defective' HIV-1 proviruses and the persistent immune activation seen in the setting of treated chronic HIV-1 infection.

Impact of very early antiretroviral therapy during acute HIV infection on long-term immunovirological outcomes

OBJECTIVES

We aimed to determine if starting antiretroviral therapy (ART) in the first 30 days after acquiring HIV infection has an impact on immunovirological response.

METHODS

Observational, ambispective study including 147 patients with confirmed acute HIV infection (January/1995-August/2022). ART was defined as very early (≤30 days after the estimated date of infection), early (31-180 days), and late (>180 days). We compared time to viral suppression (viral load [VL] <50 copies/ml) and immune recovery (IR) (CD4+/CD8+ ratio ≥1) according to the timing and type of ART using survival analysis.

RESULTS

ART was started in 140 (95.2%) patients. ART was very early in 24 (17.1%), early in 77 (55.0%), and late in 39 (27.9%) cases. Integrase strand transfer inhibitor (INSTI)-based regimens were the most used in both the overall population (65%) and the very early ART group (23/24, 95.8%). Median HIV VL and CD4+/CD8+ ratio pre-ART were higher in the very early ART group (P <0.05). Patients in the very early and early ART groups and treated with INSTI-based regimens achieved IR earlier (P <0.05). Factors associated with faster IR were the CD4+/CD8+ ratio pre-ART (hazard ratio: 9.3, 95% CI: 3.1-27.8, P <0.001) and INSTI-based regimens (hazard ratio: 2.4, 95% CI: 1.3-4.2, P = 0.003).

CONCLUSIONS

The strongest predictors of IR in patients who start ART during AHI are the CD4+/CD8+ ratio pre-ART and INSTI-based ART regimens.

An active HIV reservoir during ART is associated with maintenance of HIV-specific CD8+ T cell magnitude and short-lived differentiation status

Before initiation of antiretroviral therapy (ART), HIV-specific CD8+ T cells are dysfunctional and short lived. To better understand the relationship between the HIV reservoir in CD4+ T cells and the magnitude and differentiation status of HIV-specific CD8+ T cells, we investigated these cells from acute and chronic HIV-infected individuals after 2 years of ART. Although both the HIV reservoir and the CD8+ T cell responses declined significantly after 2 years of ART, sustained HIV-specific CD8+ T cell responses correlated with a greater reduction of integrated HIV provirus. However, the magnitude of CD8+ T cells specific for HIV Gag, Pol, Nef, and Vif proteins positively associated with the active reservoir size during ART, measured as cell-associated RNA. Importantly, high HIV DNA levels strongly associate with maintenance of short-lived HIV-specific CD8+ T cells, regardless of ART initiation time. Our data suggest that the active reservoir maintains HIV-specific CD8+ T cell magnitude but prevents their differentiation into functional cells.

CD8+ cells and small viral reservoirs facilitate post-ART control of SIV replication in M3+ Mauritian cynomolgus macaques initiated on ART two weeks post-infection

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). None of the MCMs possessed MHC haplotypes previously associated with SIV control. For six months after ART withdrawal, we observed undetectable or transient viremia in seven of the eight MCMs, despite detecting replication competent SIV using quantitative viral outgrowth assays. In vivo depletion of CD8α+ cells induced rebound in all animals, indicating the observed PTC was mediated, at least in part, by CD8α+ cells. With intact proviral DNA assays, we found that MCMs had significantly smaller viral reservoirs two wpi than a cohort of identically infected rhesus macaques, a population that rarely develops PTC. We found a similarly small viral reservoir among six additional SIV+ MCMs in which ART was initiated at eight wpi, some of whom exhibited viral rebound. These results suggest that an unusually small viral reservoir is a hallmark among SIV+ MCMs. By evaluating immunological differences between MCMs that did and did not rebound, we identified that PTC was associated with a reduced frequency of CD4+ and CD8+ lymphocyte subsets expressing exhaustion markers. Together, these results suggest a combination of small reservoirs and immune-mediated virus suppression contribute to PTC in MCMs. Further, defining the immunologic mechanisms that engender PTC in this model may identify therapeutic targets for inducing durable HIV remission in humans.

Perceptions toward antiretroviral therapy and delayed ART initiation among people living with HIV in Changsha, China: mediating effects of treatment willingness

Introduction

Delayed antiretroviral therapy (ART) initiation is associated with poor HIV outcomes and a higher likelihood of HIV transmission.

Methods

This cross-sectional study assessed the proportion of delayed ART initiation which was defined as initiating ART after 30 days of HIV diagnosis, and evaluated the pathways influencing ART initiation among adult PLWH in Changsha, China who were diagnosed between 2014 and 2022.

Results

Of 518 participants, 37.8% delayed in initiating ART. Based on the theory of reasoned action (TRA), delayed initiation was indirectly associated with perceptions toward ART through the mediating pathway of patients' treatment willingness, with treatment willingness significantly being the full mediator.

Discussion

The findings may guide the development of interventions to improve timely uptake of ART in people who are newly diagnosed with HIV.

HIV Tissue Reservoirs: Current Advances in Research

Acquired immunodeficiency syndrome (AIDS), caused by the human immunodeficiency virus (HIV), has become a heavy burden of disease and an important public health problem in the world. Although current antiretroviral therapy (ART) is effective at suppressing the virus in the blood, HIV still remains in two different types of reservoirs-the latently infected cells (represented by CD4⁺ T cells) and the tissues containing those cells, which may block access to ART, HIV-neutralizing antibodies and latency-reversing agents. The latter is the focus of our review, as blood viral load drops below detectable levels after ART, a deeper and more systematic understanding of the HIV tissue reservoirs is imperative. In this review, we take the lymphoid system (including lymph nodes, gut-associated lymphoid tissue, spleen and bone marrow), nervous system, respiratory system, reproductive system (divided into male and female), urinary system as the order, focusing on the particularity and importance of each tissue in HIV infection, the infection target cell types of each tissue, the specific infection situation of each tissue quantified by HIV DNA or HIV RNA and the evidence of compartmentalization and pharmacokinetics. In summary, we found that the present state of HIV in different tissues has both similarities and differences. In the future, the therapeutic principle we need to follow is to respect the discrepancy on the basis of grasping the commonality. The measures taken to completely eliminate the virus in the whole body cannot be generalized. It is necessary to formulate personalized treatment strategies according to the different characteristics of the HIV in the various tissues, so as to realize the prospect of curing AIDS as soon as possible.

Low genitourinary tract risks in women living with the human immunodeficiency virus

This review analyzes the clinical associations between specific low genitourinary tract clinical circumstances in perimenopausal and postmenopausal women living with human immunodeficiency virus (WLHIV). Modern antiretroviral therapy (ART) improves survival and reduces opportunistic infections and HIV transmission. Despite appropriate ART, WLHIV may display menstrual dysfunction, risk of early menopause, vaginal microbiome alterations, vaginal dryness, dyspareunia, vasomotor symptoms and low sexual function as compared to women without the infection. They have increased risks of intraepithelial and invasive cervical, vaginal and vulvar cancers. The reduced immunity capacity may also increase the risk of urinary tract infections, side-effects or toxicity of ARTs, and opportunistic infections. Menstrual dysfunction and early menopause may contribute to the early onset of vascular atherosclerosis and plaque formation, and increased osteoporosis risks requiring specific early interventions. On the other hand, the association between being postmenopausal and having a low sexual function is significant and related to low adherence to ART. WLHIV deserve a specific approach to manage different low genitourinary risks and complications related to hormone dysfunction and early menopause.

Association Between the Development of Subclinical Cardiovascular Disease and Human Immunodeficiency Virus (HIV) Reservoir Markers in People With HIV on Suppressive Antiretroviral Therapy

We report that people with human immunodeficiency virus (HIV) diagnosed with coronary artery atherosclerotic plaques display higher levels of HIV DNA compared with those without atherosclerotic plaques. In a multivariable prediction model that included 27 traditional and HIV-related risk factors, measures of HIV DNA were among the most important predictors of atherosclerotic plaque formation.

Monocyte-derived macrophages contain persistent latent HIV reservoirs

The development of persistent cellular reservoirs of latent human immunodeficiency virus (HIV) is a critical obstacle to viral eradication since viral rebound takes place once anti-retroviral therapy (ART) is interrupted. Previous studies show that HIV persists in myeloid cells (monocytes and macrophages) in blood and tissues in virologically suppressed people with HIV (vsPWH). However, how myeloid cells contribute to the size of the HIV reservoir and what impact they have on rebound after treatment interruption remain unclear. Here we report the development of a human monocyte-derived macrophage quantitative viral outgrowth assay (MDM-QVOA) and highly sensitive T cell detection assays to confirm purity. We assess the frequency of latent HIV in monocytes using this assay in a longitudinal cohort of vsPWH (n = 10, 100% male, ART duration 5-14 yr) and find half of the participants showed latent HIV in monocytes. In some participants, these reservoirs could be detected over several years. Additionally, we assessed HIV genomes in monocytes from 30 vsPWH (27% male, ART duration 5-22 yr) utilizing a myeloid-adapted intact proviral DNA assay (IPDA) and demonstrate that intact genomes were present in 40% of the participants and higher total HIV DNA correlated with reactivatable latent reservoirs. The virus produced in the MDM-QVOA was capable of infecting bystander cells resulting in viral spread. These findings provide further evidence that myeloid cells meet the definition of a clinically relevant HIV reservoir and emphasize that myeloid reservoirs should be included in efforts towards an HIV cure.

Immune Reconstitution Inflammatory Syndrome in People Living with HIV Who Presented with Interstitial Pneumonitis: an Emerging Challenge in the Era of Rapid Initiation of Antiretroviral Therapy

Studies on immune reconstitution inflammatory syndrome (IRIS) in people living with HIV (PLWH) and presenting with interstitial pneumonitis (IP) are limited in the era of rapid antiretroviral therapy (ART) initiation, particularly with integrase strand-transfer inhibitor (INSTI)-containing regimens. Adult PLWH presenting with IP in whom ART was initiated within 30 days of IP diagnosis between 2015 and 2021 were retrospectively identified. The primary outcome was the occurrence of IRIS within 30 days after admission. Of 88 eligible PLWH with IP (median age, 36 years; CD4 count, 39 cells/mm3), Pneumocystis jirovecii and cytomegalovirus (CMV) DNA were detected via polymerase-chain-reaction assay in 69.3% and 91.7% of respiratory specimens, respectively. 22 PLWH (25.0%) had manifestations that met French's IRIS criteria for paradoxical IRIS. There were no statistically significant differences in terms of the all-cause mortality (0.0% versus 6.1%, P = 0.24), the occurrence of respiratory failure (22.7% versus 19.7%, P = 0.76), and pneumothorax (9.1% versus 7.6%, P = 0.82) between PLWH with and those without paradoxical IRIS. In a multivariable analysis, the factors associated with IRIS were the decline of the 1 month plasma HIV RNA load (PVL) with ART (adjusted hazard ratio [aHR] per 1 log decrease, 3.45; 95% CI, 1.52 to 7.81), a baseline CD4-to-CD8 ratio of <0.1 (aHR, 3.47; 95% CI, 1.16 to 10.44), and the rapid initiation of ART (aHR, 7.95; 95% CI, 1.04 to 60.90). In conclusion, we found a high rate of paradoxical IRIS among PLWH with IP in the era of rapid ART initiation with INSTI-containing ART and this was associated with immune depletion at baseline, a rapid decline of PVL, and an interval of <7 days between the diagnosis of IP and the initiation of ART. IMPORTANCE Our study of PLWH who presented with IP mainly due to Pneumocystis jirovecii demonstrates that a high rate of paradoxical IRIS and a rapid decline of PVL with the initiation of ART, a CD4-to-CD8 ratio of <0.1 at baseline, and a short interval (<7 days) between the diagnosis of IP and the initiation of ART were associated with paradoxical IP-IRIS in PLWH. Paradoxical IP-IRIS was not associated with mortality or respiratory failure with heightened awareness among the HIV-treating physicians, rigorous investigations to exclude the possibilities of concomitant infections, or the malignancies and adverse effects of medications, including the cautious use of corticosteroids.

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.

Profound phenotypic and epigenetic heterogeneity of the HIV-1-infected CD4+ T cell reservoir

Understanding the complexity of the long-lived HIV reservoir during antiretroviral therapy (ART) remains a considerable impediment in research towards a cure for HIV. To address this, we developed a single-cell strategy to precisely define the unperturbed peripheral blood HIV-infected memory CD4+ T cell reservoir from ART-treated people living with HIV (ART-PLWH) via the presence of integrated accessible proviral DNA in concert with epigenetic and cell surface protein profiling. We identified profound reservoir heterogeneity within and between ART-PLWH, characterized by new and known surface markers within total and individual memory CD4+ T cell subsets. We further uncovered new epigenetic profiles and transcription factor motifs enriched in HIV-infected cells that suggest infected cells with accessible provirus, irrespective of reservoir distribution, are poised for reactivation during ART treatment. Together, our findings reveal the extensive inter- and intrapersonal cellular heterogeneity of the HIV reservoir, and establish an initial multiomic atlas to develop targeted reservoir elimination strategies.

Lessons for Understanding Central Nervous System HIV Reservoirs from the Last Gift Program

PURPOSE OF REVIEW

Deep tissue HIV reservoirs, especially within the central nervous system (CNS), are understudied due to the challenges of sampling brain, spinal cord, and other tissues. Understanding the cellular characteristics and viral dynamics in CNS reservoirs is critical so that HIV cure trials can address them and monitor the direct and indirect effects of interventions. The Last Gift program was developed to address these needs by enrolling altruistic people with HIV (PWH) at the end of life who agree to rapid research autopsy.

RECENT FINDINGS

Recent findings from the Last Gift emphasize significant heterogeneity across CNS reservoirs, CNS compartmentalization including differential sensitivity to broadly neutralizing antibodies, and bidirectional migration of HIV across the blood-brain barrier. Our findings add support for the potential of CNS reservoirs to be a source of rebounding viruses and reseeding of systemic sites if they are not targeted by cure strategies. This review highlights important scientific, practical, and ethical lessons learned from the Last Gift program in the context of recent advances in understanding the CNS reservoirs and key knowledge gaps in current research.

Adaptation to HLA-associated immune pressure over the course of HIV infection and in circulating HIV-1 strains

Adaptation to human leukocyte antigen (HLA)-associated immune pressure represents a major driver of human immunodeficiency virus (HIV) evolution at both the individual and population level. To date, there has been limited exploration of the impact of the initial cellular immune response in driving viral adaptation, the dynamics of these changes during infection and their effect on circulating transmitting viruses at the population level. Capturing detailed virological and immunological data from acute and early HIV infection is challenging as this commonly precedes the diagnosis of HIV infection, potentially by many years. In addition, rapid initiation of antiretroviral treatment following a diagnosis is the standard of care, and central to global efforts towards HIV elimination. Yet, acute untreated infection is the critical period in which the diversity of proviral reservoirs is first established within individuals, and associated with greater risk of onward transmissions in a population. Characterizing the viral adaptations evident in the earliest phases of infection, coinciding with the initial cellular immune responses is therefore relevant to understanding which changes are of greatest impact to HIV evolution at the population level. In this study, we utilized three separate cohorts to examine the initial CD8+ T cell immune response to HIV (cross-sectional acute infection cohort), track HIV evolution in response to CD8+ T cell-mediated immunity over time (longitudinal chronic infection cohort) and translate the impact of HLA-driven HIV evolution to the population level (cross-sectional HIV sequence data spanning 30 years). Using next generation viral sequencing and enzyme-linked immunospot interferon-gamma recall responses to peptides representing HLA class I-specific HIV T cell targets, we observed that CD8+ T cell responses can select viral adaptations prior to full antibody seroconversion. Using the longitudinal cohort, we uncover that viral adaptations have the propensity to be retained over time in a non-selective immune environment, which reflects the increasing proportion of pre-adapted HIV strains within the Western Australian population over an approximate 30-year period.

Immune activation in primary HIV: influence of duration of infection, treatment, and substance use

Background

Primary human immunodeficiency virus (HIV) is characterized by dynamic changes in viral load and innate and adaptive immune responses; it is unclear the extent to which time from acquisition to antiretroviral therapy (ART) initiation and substance use impact these immunologic changes.

Methods

We studied plasma immune activation biomarkers, viral load, and CD4⁺ and CD8⁺ cell counts in participants from the Sabes primary infection study in Peru, who had been randomized to begin ART immediately after diagnosis vs 24 weeks later. We modeled influence of substance use and duration of HIV infection on biomarkers at baseline and over 24 weeks.

Results

Compared to participants enrolled >30 days after HIV acquisition, participants enrolled during acute infection (≤30 days) had higher mean interferon (IFN)–γ and IFN-α2a (1.7-fold and 3.8-fold interquartile range [IQR] higher, respectively). Participants enrolled >30 days after HIV acquisition had higher mean baseline CD8⁺ cell count (2.7 times the IQR). Alcohol use (positive phosphatidylethanol level) was associated with elevated IFN-γ, tumor necrosis factor alpha (TNF-α), and interleukin 12p70 (IL-12p70), and smoking was associated with higher macrophage inflammatory protein 1α, TNF-α, and IL-12p70. Most biomarkers declined more quickly in participants who initiated ART immediately; however, substance use and duration of HIV infection at enrollment had little influence on rate of decline.

Conclusions

IFN-γ and other biomarkers are elevated during early primary infection, when exposure to HIV antigens is high. Immune activation decreased most quickly in those who started ART during acute/early primary infection. Higher CD8⁺ cell counts and a trend toward higher soluble CD163 levels during the 30 days after acquisition suggest the onset of compensatory responses and immune exhaustion.

HIV Disease Dynamics and Markers of Inflammation and CNS Injury During Primary HIV Infection and Their Relationship to Cognitive Performance

INTRODUCTION

Early systemic and central nervous system viral replication and inflammation may affect brain integrity in people with HIV, leading to chronic cognitive symptoms not fully reversed by antiretroviral therapy (ART). This study examined associations between cognitive performance and markers of CNS injury associated with acute HIV infection and ART.

METHODS

HIV-infected MSM and transgender women (average age: 27 years and education: 13 years) enrolled within 100 days from the estimated date of detectable infection (EDDI). A cognitive performance (NP) protocol was administered at enrollment (before ART initiation) and every 24 weeks until week 192. An overall index of cognitive performance (NPZ) was created using local normative data. Blood (n = 87) and cerebrospinal fluid (CSF; n = 29) biomarkers of inflammation and neuronal injury were examined before ART initiation. Regression analyses assessed relationships between time since EDDI, pre-ART biomarkers, and NPZ.

RESULTS

Adjusting for multiple comparisons, shorter time since EDDI was associated with higher pre-ART VL and multiple biomarkers in plasma and CSF. NPZ scores were within the normative range at baseline (NPZ = 0.52) and at each follow-up visit, with a modest increase through week 192. Plasma or CSF biomarkers were not correlated with NP scores at baseline or after ART.

CONCLUSIONS

Biomarkers of CNS inflammation, immune activation, and neuronal injury peak early and then decline during acute HIV infection, confirming and extending results of other studies. Neither plasma nor CSF biomarkers during acute infection corresponded to NP scores before or after sustained ART in this cohort with few psychosocial risk factors for cognitive impairment.