CROI 2024 Abstract eBook

Abstract eBook

Poster Abstracts

366

Positive Reinforcement Training Reduces Stress in SIV-Infected Macaque Models of HIV Infection Selena M. Guerrero-Martin 1 , Bess W. Carlson 1 , Samuel A. Brill 1 , Erin N. Shirk 1 , Suzanne Queen 1 , Leah H. Rubin 1 , Melanie J. Graham 2 , Lydia M. Hopper 1 , Lucio Gama 1 , Christine Zink 1 , Joseph Mankowski 1 , Janice E. Clements 1 , Kelly A Metcalf Pate 1 1 The Johns Hopkins University School of Medicine, Baltimore, MD, USA, 2 University of Minnesota, Minneapolis, MN, USA Background: Work with SIV infected macaque models is essential to HIV pathogenesis, vaccine development and cure research. Positive reinforcement training (PRT) may be used rather than restraint or sedation to facilitate administration injectable antiretroviral therapy (ART) or obtain blood samples. The effect of PRT on data in these models has yet to be defined. Methods: A subset of juvenile male rhesus (Macaca mulatta) and pigtailed (Macaca nemestrina) macaques were trained using PRT to voluntarily present a limb for ART injection and blood sampling prior to intravenous infection with SIVmac251 or SIV17E/Fr combined with SIV delta B670, respectively, and compared to untrained SIV infected macaques, and subsequently treated with ART to suppress viral replication. Regardless of training history, macaques were sedated throughout infection to obtain blood and cerebral spinal fluid. Viral loads, immune markers, and plasma cortisol levels were compared between trained and untrained SIV infected macaques (M. mulatta; n = 24 trained; n = 8 untrained; M. nemestrina n = 6 trained; n = 29 untrained) throughout the course of infection using a mixed effects model. Results: No differences were observed between trained and untrained M. mulatta in peripheral or central nervous system (CNS) viral loads during acute infection, though trained M. nemestrina demonstrated significantly lower viral loads compared to untrained macaques; no differences in viral suppression were observed upon ART initiation in either species. CD4 T cell numbers declined in all animals during acute SIV infection, with trained rhesus macaques demonstrating a delay to decline compared to untrained animals. Though all macaques experienced increased plasma cortisol following SIV infection, trained macaques had a lesser increase compared to untrained animals. Conclusion: PRT buffers the physiologic stress associated with SIV infection in macaques, as evidenced by a less pronounced cortisol response to infection. Further work needs to be completed to understand the extent to which PRT may affect viral load and immune parameters, and caution should be exercised when comparing data from animals that have engaged in PRT compared to untrained macaques. HIV Rapid Intra-Host Evolution Allows Evasion From VRC01 Infusion via Positive Selection Frida Belinky , Sung Hee Ko, Pierce Radecki, Vanessa Guerra|, Emily Coates, Pamela Costner, Julie Ledgerwood, John R. Mascola, Eli Boritz National Institutes of Health, Bethesda, MD, USA Background: One of the factors contributing to HIV's persistence is its rapid evolution. Understanding how the env gene evolves under antibody-mediated pressure is particularly important for efforts to use antibodies as therapies for HIV. In a previous clinical trial, infusion of the broadly-neutralizing antibody (bNAb) VRC01, which targets the CD4 receptor binding site, lowered plasma HIV viremia in a subset of participants, but was associated with the emergence of neutralization-resistant env variants. Here we sought to develop an analytical approach for identifying env mutations that confer escape from antibodies using single-genome sequence data from participants treated with VRC01. Methods: We applied single-genome amplification and sequencing (HT-SGS) using unique molecular identifiers (UMIs) and the Pacific Biosciences long-read platform, to measure HIV env allele frequency changes over time in longitudinal samples from people with chronic, untreated HIV infection who received one dose of VRC01. Eight participants were studied, and a total of 29,433 sequences were analyzed. We used two approaches to identify changes adaptive to VRC01 escape: (1) a codon-based dN/dS approach executed by HYPHY with FUBAR (2) a population genetics approach where Tajima's D was used to identify positive selective sweeps along the env gene, and then a score for the selected allele favored in evolution (SAFE) was calculated. Results: In six of eight hosts the viral populations pre and post infusion were distinct. Specifically, changes in the VRC01 epitope were observed. In two individuals, both FUBAR and SAFE approaches identified the same positions as adaptive. In another four individuals FUBAR and SAFE pointed to different residues as adaptive. Examining manually regions of selective sweeps as

microbiome, intestinal immunity, and susceptibility to rectal HIV acquisition have not been empirically assessed. Methods: We administered enemas (Normosol-R) to rhesus macaques (Control/Enema, n=6/6) thrice-weekly, prior to repeated low-dose intra-rectal SIVmac239X challenge. Before and 28 days after enema treatment initiation (n=12 enemas) we assessed the fecal microbiome by 16S Illumina sequencing and surveyed intestinal and systemic immunity by flow cytometry, multiplex immunologic transcript quantification (NanoString), and ELISA. Fifty-six days after enema initiation (n=24 enemas) we challenged animals with 4 TCID 50 SIVmac239X until infection was confirmed. Susceptibility to SIV infection in our animals was assessed both by time to SIV infection and number of acquired transmitter-founder (T/F) variants. Results: Prior to SIV challenge, we observed that as compared to control animals, repeated enema administration was associated with fewer memory CD4+ T-cells in the jejunum (p<0.001) and fewer memory CD4+ (p=0.032) and CD8+ (p=0.016) T-cells in the peripheral blood of treated animals. Treatment was also associated with a trend for less IL-22 production from intestinal memory CD4+ T-cells. No post-treatment differences were observed in plasma sCD14 or iFABP2. Few differences were observed in the composition of the fecal microbiome, with enema treated animals displaying perturbations in the representation of some Oscillospirales species. Of animals infected thus far (n=3/6 each group), there are no differences in the number of challenges that resulted in successful infection nor in the number of acquired T/F variants. Conclusion: Our analyses will provide a detailed assessment of how the microbiome and intestinal immunity change in response to repeated enema usage. Insight gained from our comprehensive study will inform the causes and consequences of repeated enema usage in MSM and will inform the design of improved bowel- clearing preparations for sexual and surgical use. SIV Infection in Sooty Mangabeys Does Not Impact Survival but Changes Cause of Death Cristina Ceriani , Brianne Beisner, Maria Crane, Joyce Cohen, Ian N. Moore, Deanna A. Kulpa, Guido Silvestri Emory University, Atlanta, GA, USA Background: Sooty mangabeys (SMs) are natural host of simian immunodeficiency virus (SIV), and do not progress to AIDS despite high viral replication. The main factors involved in the benign nature of this infection are (i) low level of immune activation, (ii) relative preservation of specific CD4+ T-cell subsets from direct virus infection, and (iii) absence of microbial translocation from the gut to the systemic circulation. Extensive documentation supports the non-pathogenic nature of SIV infection in SMs, with no significant disparities observed between SIV-infected and uninfected SMs. Methods: To better assess the long-term impact of SIV infection on the overall clinical conditions of SMs, we have conducted a systematic analysis of the causes of death in 307 SMs, of which 219 SIV-infected and 88 uninfected, that were housed at ENPRC and have died of natural (i.e., non- experimental) causes between1986 and 2022. Results: We found that SIV-infected SMs live ~4 years longer than SIV uninfected SMs, although this result is hard to interpret due to differences in the way animals were housed and included in specific experimental studies. While the causes of death were not different between SIV-infected and uninfected SMs that died before age 15, we found a significant differences in the relative frequency of specific causes of death in the geriatric population (≥15 y.o.). Specifically, we observed that SIV-infected SMs were more likely to die from infections (Odds Ratio (OR) +infinity, 95% CI 2.07- +infinity, P = 0.0064) but less likely to die from cardiovascular disease (OR 0.2326, 95% CI 0.104-0.675, P = 0.00613) as compared to uninfected animals. A similar trend was consistently observed within the subgroups categorized by sex, indicating that these findings were robust across sexes. No differences were observed for cancer, diabetes, trauma, and miscellaneous other causes. Conclusion: While confirming the non-pathogenic nature of SIV infection in SMs, these data reveal, for the first time, a qualitative impact of SIV infection on the host physiology that induces a significant change in the pattern of mortality in these natural SIV hosts.

Poster Abstracts

365

367

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CROI 2024