CROI 2024 Abstract eBook

Abstract eBook

Poster Abstracts

times in the coronal sulcus than Corynebacterium, a ubiquitous skin-associated bacterium, and 43% of participants had at least one visit with a BASIC above the high-risk abundance threshold (Fig. 1B). Conclusion: BASICs were detectable in the coronal sulcus of nearly two-thirds of uncircumcised participants over an 8-week study period, although only 9-17% of individuals were persistently colonized by a single BASIC species. High abundance colonization by BASICs is transient and uncommon. Targeted interventions to reduce BASIC abundance in the coronal sulcus may be an effective approach to decrease HIV risk.

consenting. They collected data via REDCap at baseline, with follow-up conducted within 10 days post enrollment. Baseline data captured socio demographics, use of ECP, HIV risk perception, HIV testing history, willingness to test for HIV and willingness to initiate PEP. Post survey data captured their experience in seeking HIV testing and PEP. Participants were issued an information sheet on HIV testing and PEP and those interested referred to nearby health facilities for services. Data were summarized using descriptive statistics. Results: We screened 297 AGYW and enrolled 200; mean age was 22 years; 90.0% were single; 10.0%, 41.7% and 48.2% had primary, secondary, and post secondary education, respectively. 41.5% perceived themselves to be at high HIV risk and 28.5% at medium risk; 28.5% felt at low-no risk despite seeking ECP. Table 1 shows those willing to test for HIV and to initiate PEP compared to those who actually went for testing after being educated on why they would be eligible. Overall, 50.7% AGWY took up testing compared to 95.5% who were willing. The most preferred testing modality was self-testing but since this was unavailable, most tested at the pharmacy; 25% tested at government facilities. Of those who tested, 80.2% tested within 3 days of enrolment. The 49.3% who did not test/take PEP cited low perceived risk (20.3%), fear of knowing HIV status (10.8%), awareness of partner's status (9.5%), distance (6.8%), and procrastination (20.3%) as barriers. Conclusion: The findings underscore the potential of pharmacies to enhance access to HIV testing and PEP initiation among at-risk AGYW by providing convenient outreach points Sydney G Nelson 1 , Ronald M. Galiwango 2 , Daniel E. Park 1 , Sanja Huibner 3 , Juan E. Salazar 1 , Maliha Aziz 1 , Edward Sung 1 , Aggrey Anok 2 , James Nnamutete 2 , John Bosco Wasswa 2 , Godfrey Kigozi 2 , Aaron A. R. Tobian 4 , Jessica L. Prodger 5 , Rupert Kaul 3 , Cindy Liu 1 1 George Washington University, Washington, DC, USA, 2 Rakai Health Sciences Program, Kalisizo, Uganda, 3 University of Toronto, Toronto, Canada, 4 The Johns Hopkins University School of Medicine, Baltimore, MD, USA, 5 Western University, London, Canada Background: Studies have defined specific penile anaerobic bacteria associated with HIV Seroconversion, Inflammation and Cells (BASICs) in uncircumcised men. However, little is known regarding the colonization dynamics of BASICs in the coronal sulcus, or if they colonize other male genital tract sites outside of the coronal sulcus. Methods: Swabs from 97 uncircumcised men were collected at the coronal sulcus, outer foreskin, penis shaft, and distal urethra in a cross-sectional study in Rakai, Uganda; 47 participants were then sampled longitudinally over 8 weeks. We characterized the penile microbiome and determined three key BASICs ( Prevotella bivia , Peptostreptococcus anaerobius , and Dialister micraerophilus ) prevalence, proportional and absolute abundance by 16S rRNA qPCR and V3V4 amplicon sequencing. We compared overall microbiome composition by PerMANOVA and BASIC abundances between sites by pair-wise Mann-Whitney Test. We also compared stability of BASICs in the coronal sulcus to other penile commensal bacteria using residence and return times, which measure the time between disappearance and subsequent re-emergence of a taxon, respectively. We imputed abundance thresholds associated with increased HIV seroconversion risk for P. bivia , P. anaerobius , and D. micraerophilus using published data (Prodger et al., 2021) to characterize dynamics of BASICs abundance over the 8-week study. Results: Overall microbiome composition differed significantly across penile sites, with BASICs most prevalent and abundant in the coronal sulcus as compared to other sites. In most study participants, P. bivia, P. anaerobius, and D. micraerophilus were detected at least once over the 8-week study period (62%, 70%, 64%, respectively), but fewer participants were colonized at all visits (17%, 17%, and 9% respectively) (Fig. 1A). All BASICs had shorter residence

Poster Abstracts

1175 Vaginal Immune Dysregulation in Transgender/Non-Binary Individuals on Masculinizing Hormone Therapy Matilde P Jacobson 1 , Janja Kovacic 1 , Eleanor Capozzi 1 , Megan Gooding 1 , Huberth Garcia 1 , Fernando Cabezas Mejia 1 , Janelle Schrag 2 , Lynsay MacLaren 2 , Christopher Cannon 2 , Mimi Ghosh 1 1 George Washington University, Washington, DC, USA, 2 Whitman-Walker Health, Washington, DC, USA Background: Many transgender men and non-binary (TMNB) people receiving gender-affirming care take synthetic testosterone as part of their masculinizing hormone therapy (MHT) regimen. This population is disproportionately affected by HIV and other sexually transmitted infections (STIs). Testosterone is known to have immunosuppressive activity and may modulate HIV/STI susceptibility. Yet little is known about the immunological characteristics of the vaginal mucosa in people assigned female at birth (AFAB) on MHT. Our objective in this study was to characterize the vaginal immune microenvironment of AFAB TMNB individuals on MHT to provide baseline immunological knowledge and guide future research. Methods: We recruited 72 AFAB participants from the Washington, DC metro area (aged 18-44, sexually active, HIV-negative) and conducted a cross-sectional study comparing 36 TMNB participants who had been on MHT for at least six months with a control group of 36 cisgender/non-binary participants not on MHT. Participants provided clinical and demographic data and self-collected vaginal swabs. The concentrations of a panel of inflammatory and antimicrobial immune biomarkers in samples were assessed by ELISA. Statistical analyses were performed using Mann-Whitney U tests to compare biomarker values between the MHT and non-MHT groups (GraphPad Prism 10.0.2). Results: Compared to non-MHT controls, the MHT group had significantly elevated levels of inflammatory biomarkers Myeloperoxidase (p=0.0101), TNFα (p=0.0053), and MIP1α (p<0.0001). The MHT group also had significantly lower levels of antimicrobial biomarkers Elafin (p<0.001), SLPI (p=0.0085), and Human Beta-Defenisn-2 (p=0.0033) compared to the control group. Age, race, income, hormonal contraceptive use, and sexual behavior were similar between the groups. Conclusion: We found evidence of vaginal immune dysregulation in TMNB individuals receiving MHT. Dysregulation of inflammatory and antimicrobial biomarkers is a potential underlying mechanism that can affect HIV/STI susceptibility. Our findings add to the scant body of knowledge available on the immunomodulatory effects of synthetic testosterone in the vagina and may inform future studies on sexual health in TMNB. Our findings do not negate MHT as a clinically safe standard of care in TMNB, but point to an indication for integrating HIV/STI prevention services into gender-affirming care programs for individuals on MHT.

1174 Stability of Penile Bacteria Associated With HIV Seroconversion, Inflammation, and Cells (BASICs)

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