Longitudinal Dynamics of Intact HIV Proviral DNA and Outgrowth Virus Frequencies in a Cohort of Individuals Receiving Antiretroviral Therapy.

BACKGROUND: The replication-competent human immunodeficiency virus (HIV) reservoir is the major barrier to cure. The quantitative viral outgrowth assay (QVOA), the gold-standard method to quantify replication-competent HIV, is resource intensive, which limits its application in large clinical trials. The intact proviral DNA assay (IPDA) requires minimal cell input relative to QVOA and quantifies both defective and intact proviral HIV DNA, the latter potentially serving as a surrogate marker for replication-competent provirus. However, there are limited cross-sectional and longitudinal data on the relationship between IPDA and QVOA measurements. METHODS: QVOA and IPDA measurements were performed on 156 resting CD4 T-cell (rCD4) samples from 83 antiretroviral therapy-suppressed HIV-positive participants. Longitudinal QVOA and IPDA measurements were performed on rCD4 from 29 of these participants. RESULTS: Frequencies of intact, defective, and total proviruses were positively associated with frequencies of replication-competent HIV. Longitudinally, decreases in intact proviral frequencies were strikingly similar to that of replication-competent virus in most participants. In contrast, defective proviral DNA frequencies appeared relatively stable over time in most individuals. CONCLUSIONS: Changes in frequencies of IPDA-derived intact proviral DNA and replication-competent HIV measured by QVOA are similar. IPDA is a promising high-throughput approach to estimate changes in the frequency of the replication-competent reservoir.

Measuring the Inducible, Replication-Competent HIV Reservoir Using an Ultra-Sensitive p24 Readout, the Digital ELISA Viral Outgrowth Assay.

Quantifying the inducible HIV reservoir provides an estimate of the frequency of quiescent HIV-infected cells in humans as well as in animal models, and can help ascertain the efficacy of latency reversing agents (LRAs). The quantitative viral outgrowth assay (QVOA) is used to measure inducible, replication competent HIV and generate estimations of reservoir size. However, traditional QVOA is time and labor intensive and requires large amounts of lymphocytes. Given the importance of reproducible and accurate assessment of both reservoir size and LRA activity in cure strategies, efforts to streamline the QVOA are of high priority. We developed a modified QVOA, the Digital ELISA Viral Outgrowth or DEVO assay, with ultra-sensitive p24 readout, capable of femtogram detection of HIV p24 protein in contrast to the picogram limitations of traditional ELISA. For each DEVO assay, 8-12 × 106 resting CD4 + T cells from aviremic, ART-treated HIV + participants are plated in limiting dilution and maximally stimulated with PHA, IL-2 and uninfected allogeneic irradiated PBMC. CD8-depleted PHA blasts from an uninfected donor or HIV-permissive cells (e.g., Molt4/CCR5) are added to the cultures and virus allowed to amplify for 8-12 days. HIV p24 from culture supernatant is measured at day 8 by Simoa (single molecule array, ultra-sensitive p24 assay) confirmed at day 12, and infectious units per million CD4 + T cells (IUPM) are calculated using the maximum likelihood method. In all DEVO assays performed, HIV p24 was detected in the supernatant of cultures as early as 8 days post stimulation. Importantly, DEVO IUPM values at day 8 were comparable or higher than traditional QVOA IUPM values obtained at day 15. Interestingly, DEVO IUPM values were similar with or without the addition of allogeneic CD8-depleted target PHA blasts or HIV permissive cells traditionally used to expand virus. The DEVO assay uses fewer resting CD4 + T cells and provides an assessment of reservoir size in less time than standard QVOA. This assay offers a new platform to quantify replication competent HIV during limited cell availability. Other potential applications include evaluating LRA activity, and measuring clearance of infected cells during latency clearance assays.

Impact of Biological Sex on Immune Activation and Frequency of the Latent HIV Reservoir During Suppressive Antiretroviral Therapy.

BACKGROUND: Persistent HIV infection of long-lived resting CD4 T cells, despite antiretroviral therapy (ART), remains a barrier to HIV cure. Women have a more robust type 1 interferon response during HIV infection relative to men, contributing to lower initial plasma viremia. As lower viremia during acute infection is associated with reduced frequency of latent HIV infection, we hypothesized that women on ART would have a lower frequency of latent HIV compared to men. METHODS: ART-suppressed, HIV seropositive women (n = 22) were matched 1:1 to 22 of 39 ART-suppressed men. We also compared the 22 women to all 39 men, adjusting for age and race as covariates. We measured the frequency of latent HIV using the quantitative viral outgrowth assay, the intact proviral DNA assay, and total HIV gag DNA. We also performed activation/exhaustion immunophenotyping on peripheral blood mononuclear cells and quantified interferon-stimulated gene (ISG) expression in CD4 T cells. RESULTS: We did not observe evident sex differences in the frequency of persistent HIV in resting CD4 T cells. Immunophenotyping and CD4 T-cell ISG expression analysis revealed marginal differences across the sexes. CONCLUSIONS: Differences in HIV reservoir frequency and immune activation appear to be small across sexes during long-term suppressive therapy.

Assessing the impact of AGS-004, a dendritic cell-based immunotherapy, and vorinostat on persistent HIV-1 Infection.

Approaches to deplete persistent HIV infection are needed. We investigated the combined impact of the latency reversing agent vorinostat (VOR) and AGS-004, an autologous dendritic cell immunotherapeutic, on the HIV reservoir. HIV+, stably treated participants in whom resting CD4+ T cell-associated HIV RNA (rca-RNA) increased after VOR exposure ex vivo and in vivo received 4 doses of AGS-004 every 3 weeks, followed by VOR every 72 hours for 30 days, and then the cycle repeated. Change in VOR-responsive host gene expression, HIV-specific T cell responses, low-level HIV viremia, rca-RNA, and the frequency of resting CD4+ T-cell infection (RCI) was measured at baseline and after each cycle. No serious treatment-related adverse events were observed among five participants. As predicted, VOR-responsive host genes responded uniformly to VOR dosing. Following cycles of AGS-004 and VOR, rca-RNA decreased significantly in only two participants, with a significant decrease in SCA observed in one of these participants. However, unlike other cohorts dosed with AGS-004, no uniform increase in HIV-specific immune responses following vaccination was observed. Finally, no reproducible decline of RCI, defined as a decrease of >50%, was observed. AGS-004 and VOR were safe and well-tolerated, but no substantial impact on RCI was measured. In contrast to previous clinical data, AGS-004 did not induce HIV-specific immune responses greater than those measured at baseline. More efficacious antiviral immune interventions, perhaps paired with more effective latency reversal, must be developed to clear persistent HIV infection.

Interval dosing with the HDAC inhibitor vorinostat effectively reverses HIV latency.

BACKGROUND: The histone deacetylase (HDAC) inhibitor vorinostat (VOR) can increase HIV RNA expression in vivo within resting CD4+ T cells of aviremic HIV+ individuals. However, while studies of VOR or other HDAC inhibitors have reported reversal of latency, none has demonstrated clearance of latent infection. We sought to identify the optimal dosing of VOR for effective serial reversal of HIV latency. METHODS: In a study of 16 HIV-infected, aviremic individuals, we measured resting CD4+ T cell-associated HIV RNA ex vivo and in vivo following a single exposure to VOR, and then in vivo after a pair of doses separated by 48 or 72 hours, and finally following a series of 10 doses given at 72-hour intervals. RESULTS: Serial VOR exposures separated by 72 hours most often resulted in an increase in cell-associated HIV RNA within circulating resting CD4+ T cells. VOR was well tolerated by all participants. However, despite serial reversal of latency over 1 month of VOR dosing, we did not observe a measurable decrease (>0.3 log10) in the frequency of latent infection within resting CD4+ T cells. CONCLUSIONS: These findings outline parameters for the experimental use of VOR to clear latent infection. Latency reversal can be achieved by VOR safely and repeatedly, but effective depletion of persistent HIV infection will require additional advances. In addition to improvements in latency reversal, these advances may include the sustained induction of potent antiviral immune responses capable of recognizing and clearing the rare cells in which HIV latency has been reversed. TRIAL REGISTRATION: Clinicaltrials.gov NCT01319383. FUNDING: NIH grants U01 AI095052, AI50410, and P30 CA016086 and National Center for Advancing Translational Sciences grant KL2 TR001109.