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

Assessing HIV-1 subtype C infection dynamics, therapeutic responses and reservoir distribution using a humanized mouse model

Introduction

While HIV-1 subtype C (HIV-1C) is the most prevalent and widely distributed subtype in the HIV pandemic, nearly all current prevention and therapeutic strategies are based on work with the subtype B (HIV-1B). HIV-1C displays distinct genetic and pathogenic features from that of HIV-1B. Thus, treatment approaches developed for HIV-1B need to be suitably optimized for HIV-1C. A suitable animal model will help delineate comparative aspects of HIV-1C and HIV-1B infections.

Methods

Here, we used a humanized mouse model to evaluate HIV-1C infection, disease progression, response to anti-retroviral therapy (ART) and viral rebound following therapy interruption. A limited comparative study with a prototypical subtype B virus was also performed. Viral infection, immune cell dynamics, acquisition of anti-retroviral therapy (ART) resistance and anatomical reservoir distribution following extended and interrupted therapy were compared.

Results

In comparison, lower early plasma viremia was observed with HIV-1C, but with similar rate of CD4+ T cell depletion as that of HIV-1B. Viral suppression by ART was delayed in the HIV-1C infected group with evidence, in one case, of acquired class wide resistance to integrase inhibitors, a critical component of current global therapy regimens. Also, HIV-1C infected animals displayed faster rebound viremia following ART interruption (ATI). Disparate patterns of tissue proviral DNA distribution were observed following extended ART and ATI suggestive of distinct sources of viral rebound.

Discussion

In this preliminary study, discernible differences were noted between HIV-1C and B with implications for prevention, therapeutics and curative strategies. Results from here also highlight the utility of the hu-HSC mouse model for future expanded studies in this context.

Multiparametric Immune Profiles and Their Potential Role in HIV-1 Disease Progression and Treatment

Backgrounds: The rapid initiation of highly active anti-retroviral therapy (HAART) can control HIV-1 viremia and stabilize the long-term health of people living with HIV-1 (PLWH). Despite this, individuals who are diagnosed late and exhibit poor therapeutic efficacy still pose a great challenge to global HIV management. To address this, we conducted comprehensive multiparametric immune profiling and analyzed its association with disease progression and therapeutic efficacy. Methods: Multicolor flow cytometry was used to characterize the circulating immune cell composition and cellular phenotypes in 40 treatment-naive individuals (16 chronic, 24 newly diagnosed), 26 HAART-treated individuals, and 18 healthy controls. Comparative analyses of T cell subsets, immune activation markers, and viral load signatures were performed, followed by network construction. We carried out principal component analysis and displayed the data by dimensionality reduction. Results: Persistent immune activation, dysregulated regulatory immunity, and aberrant memory differentiation markers were identified in T cells of HIV-1-infected individuals and were associated with disease progression. Additionally, HAART-treated patients which did not fully restore CD4 T cells exhibited higher levels of activated markers, suggesting possible biomarkers of therapeutic efficacy. Conclusions: This study describes changes in immune cell profiles throughout HIV-1 disease progression and explores suitable laboratory predictors for future clinical and therapeutic settings by monitoring pathological immune cell events.

Intact HIV DNA decays in children with and without complete viral load suppression

To inform cure in children living with HIV (CWH), we elucidated the dynamics and mechanisms underlying HIV persistence during antiretroviral therapy (ART). In 120 Kenyan CWH who initiated ART between 1-12 months of age, 55 had durable viral load suppression, and 65 experienced ART interruptions. We measured plasma HIV RNA levels, CD4+ T cell count, and levels of intact and defective HIV DNA proviruses via the cross-subtype intact proviral DNA assay (CS-IPDA). By modeling data from the durably suppressed subset, we found that during early ART (year 0-1 on ART), plasma RNA levels decayed rapidly and biphasically and intact and defective HIV DNA decayed with mean 3 and 9 month half-lives, respectively. After viral suppression was achieved (years 1-8 on ART), intact HIV DNA decay slowed to a mean 22 month half-life, whilst defective HIV DNA no longer decayed. In five CWH, we found individual CD4+ TCRβ clones wax and wane, but average kinetics resembled those of defective DNA and CD4 count, suggesting that differential decay of intact HIV DNA arises from selective pressures overlaying normal CD4+ T cell kinetics. Finally, by modeling HIV RNA and DNA in CWH with treatment interruptions, we linked temporary viremia to transient rises in HIV DNA, but long-term intact reservoirs were not strongly influenced, suggesting brief treatment interruptions may not significantly increase HIV reservoirs in children.

Activation of CXCR3+ Tfh cells and B cells in lymph nodes during acute HIV-1 infection correlates with HIV-specific antibody development

Lymph node T follicular helper (Tfh) cells and germinal center (GC) B cells are critical to generate potent antibodies but are rarely possible to study in humans. To understand how Tfh/GC B-cell interactions during acute HIV-1 infection (AHI) impact the generation of HIV-specific antibodies, we performed a unique cross-sectional analysis of inguinal lymph node biopsies taken prior to antiretroviral therapy (ART) initiation in AHI. Although total Tfh and GC B cell frequencies did not change during AHI, increased frequencies of proliferating Th1-like CXCR3+ Tfh, CXCR3+ non-GC B cells, and total CXCR3+ GC B cells correlated with gp120-specific IgG antibody levels in AHI. Frequencies of proliferating CXCR3+ Tfh in AHI also correlated with gp120-specific IgG antibody levels after 48 weeks of ART, antibody-dependent cellular cytotoxicity, antibody-dependent cellular phagocytosis, and increased antibody binding to infected cells after ART. Importantly, while beneficial for antibody development, CXCR3+ Tfh cells were also infected by HIV-1 at higher frequencies than their CXCR3- counterparts and may contribute to the initial dissemination of HIV-1 in follicles. Together, these data suggest that activation of CXCR3+ Tfh cells is associated with induction of the germinal center response and subsequent antibody development, making these cells an important target for future therapeutic interventions.

IMPORTANCE

Early initiation of antiretroviral therapy (ART) is important to limit the seeding of the long-lasting HIV-1 reservoir; however, it also precludes the development of HIV-specific antibodies that can help control the virus if ART is stopped. Antibody development occurs within germinal centers in the lymph node and requires activation of both antigen-specific B cells and T follicular helper cells (Tfh), a specialized CD4+ cell that provides B cell help. To understand how early ART initiation may prohibit antibody development, we analyzed the frequencies and activation status of Tfh and B cells in lymph node biopsies collected in the different stages of acute HIV-1 infection. Our data suggest that decreased antibody development after early ART initiation may be due to limited germinal center development at the time of treatment and that new interventions that target activation of CXCR3+ Tfh may be beneficial to increase long-term HIV-specific antibody levels.

Adaptive NK Cells Rapidly Expand during Acute HIV Infection and Persist Despite Early Initiation of Antiretroviral Therapy

HIV is associated with NK cell dysfunction and expansion of adaptive-like NK cells that persist despite antiretroviral therapy (ART). We investigated the timing of NK cell perturbations during acute HIV infection and the impact of early ART initiation. PBMCs and plasma were obtained from people with HIV (PWH; all men who have sex with men; median age, 26.0 y) diagnosed during Fiebig stages I, II, III, or IV/V. Participants initiated ART a median of 3 d after diagnosis, and immunophenotyping was performed at diagnosis and longitudinally after ART. Anti-CMV Abs were assessed by ELISA. Samples from matched HIV-uninfected males were also analyzed. Proportions of adaptive NK cells (A-NKs; defined as Fcε-Receptor-1γ-) were expanded at HIV diagnosis at all Fiebig stages (pooled median 66% versus 25% for controls; p < 0.001) and were not altered by early ART initiation. Abs to CMV immediate early protein were elevated in PWH diagnosed in Fiebig stages III and IV/V (p < 0.03 for both). Proportions of A-NKs defined as either Fcε-Receptor-1γ- or NKG2C+/CD57+ were significantly associated with HIV DNA levels at diagnosis (p = 0.046 and 0.029, respectively) and trended toward an association after 48 wk of ART. Proportions of activated HLA-DR+/CD38+ NK cells remained elevated in PWH despite early ART initiation. NK cell activation and A-NK expansion occur very early after HIV transmission, before T cell activation, and are not altered by ART initiation during acute infection. A-NKs may contribute to HIV control and thus be useful for HIV cure.

High monoclonal neutralization titers reduced breakthrough HIV-1 viral loads in the Antibody Mediated Prevention trials

The Antibody Mediated Prevention (AMP) trials (NCT02716675 and NCT02568215) demonstrated that passive administration of the broadly neutralizing monoclonal antibody VRC01 could prevent some HIV-1 acquisition events. Here, we use mathematical modeling in a post hoc analysis to demonstrate that VRC01 influenced viral loads in AMP participants who acquired HIV. Instantaneous inhibitory potential (IIP), which integrates VRC01 serum concentration and VRC01 sensitivity of acquired viruses in terms of both IC50 and IC80, follows a dose-response relationship with first positive viral load (p = 0.03), which is particularly strong above a threshold of IIP = 1.6 (r = -0.6, p = 2e-4). Mathematical modeling reveals that VRC01 activity predicted from in vitro IC80s and serum VRC01 concentrations overestimates in vivo neutralization by 600-fold (95% CI: 300-1200). The trained model projects that even if future therapeutic HIV trials of combination monoclonal antibodies do not always prevent acquisition, reductions in viremia and reservoir size could be expected.

Prior exposure to antiretroviral therapy among adult patients presenting for HIV treatment initiation or reinitiation in sub-Saharan Africa: a systematic review

OBJECTIVES

As countries have scaled up access to antiretroviral therapy (ART) for HIV, attrition rates of up to 30% annually have created a large pool of individuals who initiate treatment with prior ART experience. Little is known about the proportion of non-naïve reinitiators within the population presenting for treatment initiation.

DESIGN

Systematic review of published articles and abstracts reporting proportions of non-naïve adult patients initiating ART in sub-Saharan Africa.

DATA SOURCES

PubMed, Embase Elsevier, Web of Science Core Collection, International AIDS Society conferences, Conference on Retroviruses and Opportunistic Infections conferences.

ELIGIBILITY CRITERIA

Clinical trials and observational studies; reporting on adults in sub-Saharan Africa who initiated lifelong ART; published in English between 1 January 2018 and 11 July 2023 and with data collected after January 2016. Initiator self-report, laboratory discernment of antiretroviral metabolites, and viral suppression at initiation or in the medical record were accepted as evidence of prior exposure.

DATA EXTRACTION AND SYNTHESIS

We captured study and sample characteristics, proportions with previous ART exposure and the indicator of previous exposure reported. We report results of each eligible study, estimate the risk of bias and identify gaps in the literature.

RESULTS

Of 2740 articles, 11 articles describing 12 cohorts contained sufficient information for the review. Proportions of initiators with evidence of prior ART use ranged from 5% (self-report only) to 53% (presence of ART metabolites in hair or blood sample). The vast majority of screened studies did not report naïve/non-naïve status. Metrics used to determine and report non-naïve proportions were inconsistent and difficult to interpret.

CONCLUSIONS

The proportion of patients initiating HIV treatment who are truly ART naïve is not well documented. It is likely that 20%-50% of ART patients who present for ART are reinitiators. Standard reporting metrics and diligence in reporting are needed, as is research to understand the reluctance of patients to report prior ART exposure.

PROSPERO REGISTRATION NUMBER

CRD42022324136.

Impact factors of Blastocystis hominis infection in persons living with human immunodeficiency virus: a large-scale, multi-center observational study from China

BACKGROUND

Blastocystis hominis (Bh) is zoonotic parasitic pathogen with a high prevalent globally, causing opportunistic infections and diarrhea disease. Human immunodeficiency virus (HIV) infection disrupts the immune system by depleting CD4+ T lymphocyte (CD4+ T) cell counts, thereby increasing Bh infection risk among persons living with HIV (PLWH). However, the precise association between Bh infection risk and HIV-related biological markers and treatment processes remains poorly understood. Hence, the purpose of the study was to explore the association between Bh infection risk and CD4+ T cell counts, HIV viral load (VL), and duration of interruption in antiviral therapy among PLWH.

METHODS

A large-scale multi-center cross-sectional study was conducted in China from June 2020 to December 2022. The genetic presence of Bh in fecal samples was detected by real-time fluorescence quantitative polymerase chain reaction, the CD4+ T cell counts in venous blood was measured using flowcytometry, and the HIV VL in serum was quantified using fluorescence-based instruments. Restricted cubic spline (RCS) was applied to assess the non-linear association between Bh infection risk and CD4+ T cell counts, HIV VL, and duration of interruption in highly active antiretroviral therapy (HARRT).

RESULTS

A total of 1245 PLWH were enrolled in the study, the average age of PLWH was 43 years [interquartile range (IQR): 33, 52], with 452 (36.3%) being female, 50.4% (n = 628) had no immunosuppression (CD4+ T cell counts > 500 cells/μl), and 78.1% (n = 972) achieved full virological suppression (HIV VL < 50 copies/ml). Approximately 10.5% (n = 131) of PLWH had interruption. The prevalence of Bh was found to be 4.9% [95% confidence interval (CI): 3.8-6.4%] among PLWH. Significant nonlinear associations were observed between the Bh infection risk and CD4+ T cell counts (Pfor nonlinearity < 0.001, L-shaped), HIV VL (Pfor nonlinearity < 0.001, inverted U-shaped), and duration of interruption in HARRT (Pfor nonlinearity < 0.001, inverted U-shaped).

CONCLUSIONS

The study revealed that VL was a better predictor of Bh infection than CD4+ T cell counts. It is crucial to consider the simultaneous surveillance of HIV VL and CD4+ T cell counts in PLWH in the regions with high level of socioeconomic development. The integrated approach can offer more comprehensive and accurate understanding in the aspects of Bh infection and other opportunistic infections, the efficacy of therapeutic drugs, and the assessment of preventive and control strategies.