CROI 2024 Abstract eBook

Abstract eBook

Invited Session

contain weak to no secondary TACK activity and therefore are not expected to be relevant inducers of HIV-cell kill at clinical exposures. Here, we optimized this secondary activity to identify TACK compounds with potencies compatible with clinically achievable concentrations. Pre-clinical proof of concept for cell kill was demonstrated in ex vivo studies with cells from PLWH as well as in an HIV-infected humanized mouse model. These novel NNRTI-TACK molecules have a potential application in HIV cure via reduction in the viral reservoir. From Transcriptomics to Therapeutics: A Host Restriction Factor That Targets HIV Expression Rasmi Thomas Walter Reed Army Institute of Research, Silver Spring, MD, USA Background: Advances in unbiased next-generation sequencing methods for characterizing all RNA transcripts in a sample have revolutionized scientific research in the past decade, leading to discoveries related to how variation in people impacts responses to disease outcomes, vaccination and therapeutics. Transcriptomics assays expression from every gene in an organism's genome to reveal the global pattern of transcription. Measuring gene expression in different tissues, conditions, or at different times can reveal details of an organism's biology that result in differential disease outcomes. Transcriptomics was first developed as bulk RNA sequencing (RNA-seq), which yields an aggregate of all gene expression in many cells. Recent single cell RNA-seq (scRNA-seq) techniques provide transcriptomics data for individual cells, which delineate changes in each cell relative to another. This talk describes how we used scRNA-seq to measure not only the host transcripts, but also HIV RNA (vRNA) expression in people living with HIV during acute HIV-1 infection (AHI). This method allowed us to identify host factors restricting HIV-1 transcripts in vivo without any additional laboratory manipulation. A subset of CD4+ T cells with a memory phenotype had the most vRNA+ cells, recapitulating previous data using other methods. Frequency of these cells correlated with important clinical parameters like plasma viremia and cell-associated HIV DNA levels, suggesting that the identified vRNA+ cells were biologically meaningful. When analyzing viral transcripts as a continuous phenotype across individual cells, we identified several host genes for which higher expression levels associated with lower vRNA. PTMA showed the strongest association with lower vRNA expression. This observation was validated in additional participants from different world populations and HIV subtypes. PTMA expression at timepoints after initiation of treatment showed an inverse correlation with frequency of vRNA+ cell measured during AHI, suggesting that changes in PTMA even in the absence of viremia can affect viral transcript levels. In vitro overexpression experiments provided direct evidence that expression of the prothymosin α protein encoded by PTMA inhibited HIV-1 transcription and expression. These results identify prothymosin α as a host factor that restricts HIV-1 infection in vivo, which has implications for viral transmission and cure strategies. From Structure to Therapeutics: CD4 Mimetics “Open” Env and Sensitize HIV-1-Infected Cells to ADCC Andrés Finzi Centre de Recherche du CHUM, Université de Montréal, Montreal, Quebec, Canada Background: Combination antiretroviral therapy (cART) controls human immunodeficiency virus (HIV-1) replication and extends the longevity of persons living with HIV-1 (PLWH). Even with optimal cART, latent HIV-1 proviruses persist in long-lived reservoirs, from which virus rebounds within days to weeks of treatment interruption. Therefore, new approaches aimed at eliminating HIV-1 reservoirs are needed. Persistently infected cells can potentially be eliminated by harnessing host immune responses. One promising strategy relies on the ability of immune effector cells to kill infected cells expressing the HIV-1 envelope glycoprotein (Env). Non-neutralizing antibodies (Abs) targeting highly conserved CD4-induced (CD4i) Env epitopes have the potential to eliminate infected cells by antibody-dependent cellular cytotoxicity (ADCC). Unfortunately, as a countermeasure, the HIV-1 Vpu and Nef proteins downregulate CD4, preventing the exposure of ADCC-vulnerable CD4i Env epitopes. Small CD4-mimetic compounds (CD4mcs) can "open-up" Env, exposing vulnerable CD4i Env epitopes and sensitizing HIV-1-infected cells to ADCC. A cocktail of two families of CD4i Abs (anti-cluster A and anti-coreceptor binding site Abs) together with a CD4mc was shown to significantly decrease the size of the reservoir and delay viral rebound after cART interruption in humanized mice. A summary of the development of new families of CD4mc with improved potency, new cocktails of CD4i Abs with higher ADCC activity, their

unfolds with many solutions. This talk will attempt to provide an overview of exciting technological developments and solutions in HIV/STBBI screening and diagnosis. Solutions that promise efficient surveillance/tracking, education/empowerment, rapid access to testing and treatment, or an offer of personalized care lead to clinical/public health impact. We will also offer a vision of near-term scientific advancement in diagnostics. Learning objectives and outcomes After this session, participants will be able to 1) Identify the state of-the-art screening and diagnostic technologies for HIV/STBBIs 2) Identify the evidence on promising digital and machine learning technologies that will impact health service delivery. 3) Potential for digital health transformation with impact on operational and patient-centered outcomes. 4) Envision the future of diagnostics and tech-enabled digital transformation in HIV/STBBI. From Mechanisms to Therapeutics: Eliminating HIV-infected Cells by the CARD8 Inflammasome Liang Shan Washington University in St Louis, St Louis, MO, USA Background: A successful curative strategy for HIV should aim at selective elimination of HIV-infected cells. The 'shock-and-kill' approach involves inducing viral gene expression to trigger immune clearance of infected cells. One of the main obstacles is the presence of immune escape variants in HIV reservoirs. Therefore, broadly reactive T cell and antibody responses are required to overcome viral diversity. Another challenge lies in effectively triggering cell death. Immune effector cells including CD8+ T cells and NK cells induce apoptosis in target cells. However, quiescent CD4+ T cells, which are a major reservoir for the virus, are less susceptible to T cell and NK cell attacks compared to cycling T cells. Moreover, cells harboring latent HIV may undergo positive selection to become more resistant to apoptosis. To this end, our goal is to identify new immune pathways that specifically target highly conserved viral components and effectively induce cell death in HIV reservoirs. We reported that caspase recruitment domain–containing protein 8 (CARD8) is an innate immune sensor that can be activated through proteolytic cleavage of its N-terminal fragment. In HIV–infected cells, CARD8 cannot detect the virus because the viral protease remains inactive as a subunit of unprocessed Gag–Pol polyprotein. Some HIV–specific non-nucleoside reverse transcriptase inhibitors (NNRTIs) can trigger intracellular viral protease activation. Treating HIV– infected macrophages and CD4+ T cells with NNRTIs leads to CARD8-mediated caspase 1 activation and pyroptotic cell death. Targeting CARD8 for HIV reservoir elimination offers two significant advantages. Firstly, the viral protease activity against CARD8 is well conserved across major HIV subtypes. Secondly, CARD8 exhibits high functionality in quiescent CD4+ T cells and can trigger cell death independently of apoptosis. Further research should be conducted to explore and discover more potent activators of CARD8 that specifically target HIV-infected cells. This will help in enhancing the effectiveness of CARD8-based therapies for eliminating the HIV reservoir. Mechanisms to Therapeutics: TACK Molecules Kill HIV-Infected Cells Through Inflammasome Activation Tracy L Diamond Merck & Co, Inc, Rahway, NJ ,USA Background: The viral reservoir, consisting of both HIV-1–expressing and latently infected cells, necessitates life-long antiretroviral therapy (ART) to suppress HIV-1 replication in people living with HIV (PLWH). Current ART blocks viral replication and prevents spread to healthy cells. In doing this it maintains, but does not reduce, the HIV infected cell reservoir. A common approach to address the reservoir is known as "shock and kill", which seeks to reactivate latent HIV-1 such that cells can be targeted and eliminated through viral cytolysis or host cellular immunity. This approach has yielded some clinical success in inducing viral reactivation but has had little to no impact on reducing the reservoir. Cytotoxic agents that are selective for HIV-infected cells could enhance or complement such a strategy. Non-nucleoside reverse transcriptase inhibitors (NNRTIs) are common components of ART that have been designed to enzymatically block the viral reverse transcriptase (RT), however studies have demonstrated that some NNRTIs also have a secondary mechanism of action resulting in HIV-specific cell kill. Through this targeted activator of cell kill (TACK) mechanism NNRTIs enhance HIV-1 Gag-Pol dimerization causing premature HIV-1 intracellular protease maturation which induces HIV-1 cytotoxicity through CARD8 inflammasome activation. Although current marketed NNRTIs have potent RT inhibitory activity, they

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CROI 2024