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BackgroundPersistent 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.MethodsART-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.ResultsWe 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.ConclusionsDifferences in HIV reservoir frequency and immune activation appear to be small across sexes during long-term suppressive therapy.

The primary human immunodeficiency virus (HIV) reservoir is composed of resting memory CD4.sup.+ T cells, which often express the immune checkpoint receptors programmed cell death protein 1 (PD-1) and cytotoxic T lymphocyte-associated protein 4 (CTLA-4), which limit T cell activation via synergistic mechanisms. Using simian immunodeficiency virus (SIV)-infected, long-term antiretroviral therapy (ART)-treated rhesus macaques, we demonstrate that PD-1, CTLA-4 and dual CTLA-4/PD-1 immune checkpoint blockade using monoclonal antibodies is well tolerated, with evidence of bioactivity in blood and lymph nodes. Dual blockade was remarkably more effective than PD-1 blockade alone in enhancing T cell cycling and differentiation, expanding effector-memory T cells and inducing robust viral reactivation in plasma and peripheral blood mononuclear cells. In lymph nodes, dual CTLA-4/PD-1 blockade, but not PD-1 alone, decreased the total and intact SIV-DNA in CD4.sup.+ T cells, and SIV-DNA and SIV-RNA in B cell follicles, a major site of viral persistence during ART. None of the tested interventions enhanced SIV-specific CD8.sup.+ T cell responses during ART or viral control after ART interruption. Thus, despite CTLA-4/PD-1 blockade inducing robust latency reversal and reducing total levels of integrated virus, the degree of reservoir clearance was still insufficient to achieve viral control. These results suggest that immune checkpoint blockade regimens targeting PD-1 and/or CTLA-4, if performed in people living with HIV with sustained aviremia, are unlikely to induce HIV remission in the absence of additional interventions. Immune checkpoint blockade has been proposed as a potentially curative strategy to reduce the HIV reservoir. Studies in monkeys now show that this approach alone is ineffective at enabling viral control after antiretroviral treatment interruption., Author(s): Justin Harper [sup.1] , Shari Gordon [sup.2] [sup.3] , Chi Ngai Chan [sup.4] , Hong Wang [sup.1] , Emily Lindemuth [sup.5] , Cristin Galardi [sup.3] [sup.6] , Shane D. [...]

Latency reveRsaI strategies for HIV cure using inhibitor of apoptosis protein (IAP) antagonists (IAPi) induce unprecedented levels of latent reservoir expression without immunotoxicity during suppressive antiretroviral therapy (ART). However, full targeting of the reservoir may require combinatorial approaches. A Jurkat latency model screen for IAPi combination partners demonstrated synergistic latency reveRsaI with bromodomain (BD) and extraterminal domain protein inhibitors (BETi). Mechanistic investigations using CRISPR-CAS9 and single-cell RNA-Seq informed comprehensive ex vivo evaluations of IAPi plus pan-BET, bD-selective BET, or selective BET isoform targeting in [CD4.sup.+] T cells from ART-suppressed donors. IAPi+BETi treatment resulted in striking induction of cell-associated HIV gag RNA, but lesser induction of fully elongated and tat-rev RNA compared with T cell activation-positive controls. IAPi+BETi resulted in HIV protein induction in bulk cultures of [CD4.sup.+] T cells using an ultrasensitive p24 assay, but did not result in enhanced viral outgrowth frequency using a standard quantitative viral outgrowth assay. This study defines HIV transcriptional elongation and splicing as important barriers to latent HIV protein expression following latency reveRsaI, delineates the roles of BET proteins and their BDs in HIV latency, and provides a rationale for exploration of IAPi+BETi in animal models of HIV latency., Introduction HIV cure remains elusive because of latent but replication-competent HIV DNA within host [CD4.sup.+] T cells during long-term suppressive antiretroviral therapy (ART) (1, 2). HIV latency is maintained by [...]

Lifelong treatment is required for people living with HIV as current antiretroviral therapy (ART) does not eradicate HIV infection. Latently infected cells are essentially indistinguishable from uninfected cells and cannot be depleted by currently available approaches. This study evaluated antibody mediated transient CD4+ T cell depletion as a strategy to reduce the latent HIV reservoir. Anti-CD4 antibodies effectively depleted CD4+ T cells in the peripheral blood and tissues of humanized mice. We then demonstrate that antibody-mediated CD4+ T cell depletion of HIV infected ART-suppressed animals results in substantial reductions in cell-associated viral RNA and DNA levels in peripheral blood cells over the course of anti-CD4 antibody treatment. Recovery of CD4+ T cells was observed in all tissues analyzed except for the lung 26 days after cessation of antibody treatment. After CD4+ T cell recovery, significantly lower levels of cell-associated viral RNA and DNA were detected in the tissues of anti-CD4 antibody-treated animals. Further, an 8.5-fold reduction in the levels of intact HIV proviral DNA and a 3.1-fold reduction in the number of latently infected cells were observed in anti-CD4-antibody-treated animals compared with controls. However, there was no delay in viral rebound when ART was discontinued in anti-CD4 antibody-treated animals following CD4+ T cell recovery compared with controls. Our results suggest that transient CD4+ T cell depletion, a long-standing clinical intervention that might have an acceptable safety profile, during suppressive ART can reduce the size of the HIV reservoir in humanized mice. Author summary: Current long-term antiretroviral therapy does not eradicate cells latently infected with HIV. Latently HIV-infected cells are essentially indistinguishable from uninfected cells and cannot be easily targeted by currently available strategies. CD4+ T cells represent the most well-characterized and largest HIV reservoir. Anti-CD4 antibody mediated CD4+ T cells depletion has been proved to be reversible and well-tolerated in humans. In this study, we evaluated the effect of transient depletion of human CD4+ T cells with an anti-CD4 antibody on the size of the HIV reservoir in HIV-infected ART-suppressed humanized mice. CD4+ T cells in the peripheral blood and tissues of humanized mice were effectively depleted. Importantly, the size of the HIV reservoir was significantly decreased in anti-CD4 antibody treated animals following CD4+ T cell recovery compared with untreated controls. [ABSTRACT FROM AUTHOR]

We tested the combination of a broadly neutralizing HIV antibody with the latency reversal agent vorinostat (VOR). Eight participants received 2 month-long cycles of VRC07-523LS with VOR. Low-level viremia, resting CD4+ T-cell-associated HIV RNA (rca-RNA) was measured, and intact proviral DNA assay (IPDA) and quantitative viral outgrowth assay (QVOA) were performed at baseline and posttreatment. In 3 participants, IPDA and QVOA declines were accompanied by significant declines of rca-RNA. However, no IPDA or QVOA declines clearly exceeded assay variance or natural decay. Increased resistance to VRC07-523LS was not observed. This combination therapy did not reduce viremia or the HIV reservoir. Clinical Trials Registration. NCT03803605. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Histone deacetylase inhibitors (HDACi) are the most widely studied HIV latency reversing agents (LRAs). The HDACi suberoylanilidehydroxamic acid (vorinostat, VOR) has been employed in several clinical HIV latency reversal studies as well as in vitro models of HIV latency and shown to effectively induce HIV RNA and protein expression. Despite these findings, response to HDACi can vary, particularly with intermittent dosing, and information is lacking on the relationship between host transcriptional response and HIV latency reversal. Herein, we report on global gene expression responses to VOR and examined the longevity of the transcriptional response in various cellular models. We find many genes are modulated at 6 h post-VOR in HCT116, Jurkat and primary resting CD4 T cells yet return to baseline levels after an 18 h VOR-free period. With repeat exposure to VOR in resting CD4 T cells, we find similar and consistent transcriptional changes 6 h following each serial treatment. In addition, serial exposure in HIV infected suppressed donor CD4 T cells showed consistent transcriptional changes after each exposure to VOR. We identified five host genes that were strongly and consistently modulated following HDAC inhibition: 3 up-regulated (H1F0, IRGM, WIPI49) and 2 down-regulated (PHF15 and PRDM10). These genes demonstrated consistent modulation in PBMC samples from HIV+ participants who received either single or multiple doses of 400 mg VOR. Interestingly, host transcriptional response did not predict induction of cell-associated HIV RNA, suggesting other cellular factors play key roles in HIV latency reversal in vivo despite robust HDACi pharmacological activity. IMPORTANCE Histone deacetylase inhibitors are widely studied HIV latency reversing agents (LRAs). VOR, an HDACi, induces histone acetylation, chromatin remodeling, and modulates host and HIV gene expression. However, the relationship between these events are poorly defined, and clinical studies suggest diminished HIV reactivation in resting CD4 T cells with daily exposures to VOR. Our study provides evidence that VOR induces a consistent level of host cell gene transcription, following intermittent exposure. In addition, a gene signature was identified in response to VOR exposure that was conserved across single and serial exposures both in vitro and in vivo, indicating that VOR can consistently and reproducibly modulate transcriptional host responses. However, as responses to HIV response to HDACis decline over time, other factors modulate viral reactivation in vivo despite robust HDAC activity. The identified host gene VOR biomarkers can be used for monitoring the pharmacodynamic activity of HDAC inhibitors. [ABSTRACT FROM AUTHOR]

Influenza viruses are a threat to global public health resulting in ~500,000 deaths each year. Despite an intensive vaccination program, influenza infections remain a recurrent, yet unsolved public health problem. Secondary bacterial infections frequently complicate influenza infections during seasonal outbreaks and pandemics, resulting in increased morbidity and mortality. Staphylococcus aureus, including methicillin-resistant S. aureus (MRSA), is frequently associated with these co-infections, including the 2009 influenza pandemic. Damage to alveolar epithelium is a major contributor to severe influenza-bacterial co-infections and can result in gas exchange abnormalities, fluid leakage, and respiratory insufficiency. These deleterious manifestations likely involve both pathogen- and host-mediated mechanisms. However, there is a paucity of information regarding the mechanisms (pathogen- and/or host-mediated) underlying influenza-bacterial co-infection pathogenesis. To address this, we characterized the contributions of viral-, bacterial-, and host-mediated factors to the altered structure and function of alveolar epithelial cells during co-infection with a focus on the 2009 pandemic influenza (pdm2009) and MRSA. Here, we characterized pdm2009 and MRSA replication kinetics, temporal host kinome responses, modulation of MRSA virulence factors, and disruption of alveolar barrier integrity in response to pdm2009-MRSA co-infection. Our results suggest that alveolar barrier disruption during co-infection is mediated primarily through host response dysregulation, resulting in loss of alveolar barrier integrity. [ABSTRACT FROM AUTHOR]

Limited cellular levels of the HIV transcriptional activator Tat are one contributor to proviral latency that might be targeted in HIV cure strategies. We recently demonstrated that lipid nanoparticles containing HIV tat mRNA induce HIV expression in primary CD4 T cells. Here, we sought to further characterize tat mRNA in the context of several benchmark latency reversal agents (LRAs), including inhibitor of apoptosis protein antagonists (IAPi), bromodomain and extra-Terminal motif inhibitors (BETi), and histone deacetylase inhibitors (HDACi). tat mRNA reversed latency across several different cell line models of HIV latency, an effect dependent on the TAR hairpin loop. Synergistic enhancement of tat mRNA activity was observed with IAPi, HDACi, and BETi, albeit to variable degrees. In primary CD4 T cells from durably suppressed people with HIV, tat mRNA profoundly increased the frequencies of elongated, multiply-spliced, and polyadenylated HIV transcripts, while having a lesser impact on TAR transcript frequencies. tat mRNAs alone resulted in variable HIV p24 protein induction across donors. However, tat mRNA in combination with IAPi, BETi, or HDACi markedly enhanced HIV RNA and protein expression without overt cytotoxicity or cellular activation. Notably, combination regimens approached or in some cases exceeded the latency reversal activity of maximal mitogenic T cell stimulation. Higher levels of tat mRNA-driven HIV p24 induction were observed in donors with larger mitogen-inducible HIV reservoirs, and expression increased with prolonged exposure time. Combination LRA strategies employing both small molecule inhibitors and Tat delivered to CD4 T cells are a promising approach to effectively target the HIV reservoir., Competing Interests: J.V. was an employee of Arcturus and may be a stockholder. E.V.G. and D.B. were employees of Johnson & Johnson and may be stockholders. D.M.M. has consulted for Merck and ViiV, outside the area of this work, and holds common stock in Gilead. No other conflicts are declared.

The eradication of HIV infection is difficult to achieve because of stable viral reservoirs. Here, we show that crotonylation enhances AZD5582-induced noncanonical NF-κB (ncNF-κB) signaling, further augmenting HIV latency reversal in Jurkat and U1 cell line models of latency, HIV latently infected primary CD4+ T cells and resting CD4+ T cells isolated from people living with HIV. Crotonylation upregulated the levels of the active p52 subunit of NF-κB following AZD5582. Biochemical analyses suggest that the ubiquitin E3 ligase TRIM27 is involved in enhanced p100 cleavage to p52. When TRIM27 was depleted, AZD5582-induced HIV latency reversal was reduced. TRIM27 small interfering RNA (siRNA) knockdown reduced both p100 and p52 levels without inhibiting p100 transcription, indicating that TRIM27 not only acts on p100 cleavage but also may impact p100/p52 stability. These observations reveal the complexity of HIV transcriptional machinery, particularly of NF-κB., Competing Interests: GJ has a related patent application (Publication number: 20,200,268,856). Other authors declare no conflict of interest., (© 2021 The Author(s).)