Effects of Long-Acting Antiretroviral Therapy on Offspring Immunity in Rhesus Macaques

Over 1 million women living with HIV (WLWH) give birth annually. With widespread use of combination antiretroviral therapy (cART), vertical transmission has been significantly reduced, resulting in ~16 million HIV- exposed uninfected (HEU) children as of 2023. Despite being HIV negative, these children face increased risks of poor growth, infection-related mortality, and respiratory disease. These outcomes are believed to result from maternal HIV-induced inflammation and/or cART toxicity, as many antiretrovirals cross the placenta and may disrupt fetal immune development. However, distinguishing the effects of HIV versus ART is difficult in clinical studies due to challenges of studying non-HIV infected women receiving ART. Limited access to fetal tissues further hampers mechanistic insight, creating a need for translational animal models. To address this critical knowledge gap, we propose to use a rhesus macaque model of simian immunodeficiency virus (SIV) infection to investigate how maternal HIV and long-acting ART (LA-ART) affect fetal immune development. We hypothesize that despite the absence of vertical transmission, maternal SIV and LA-ART exposure dysregulates immune ontogeny in the offspring via altered hematopoiesis. A novel LA-ART regimen of FDA-approved drugs Lenacapavir (LEN) and Cabotegravir (CAB), shown to provide effective viral suppression in preliminary macaque studies, will be given bimonthly by injection to female macaques that will then undergo time-mated breeding following viral suppression. Three experimental groups will be studied: [1] SIV-infected, LA- ART treated; [2] uninfected, LA-ART treated; and [3] uninfected, untreated controls. Offspring will be delivered naturally and monitored through six months of age. Specific Aim 1 will assess how maternal SIV/LA-ART versus LA-ART alone affects infant immune maturation and function in the periphery and in tissues using flow cytometry, single-cell RNA/ATAC-sequencing, and in vitro stimulation. We will evaluate vaccine responsiveness using Varivax™ and examine B/T cell responses and receptor repertoires. Specific Aim 2 will study the impact of maternal SIV/LA-ART versus LA-ART alone on hematopoiesis in the offspring. We hypothesize that SIV/LA-ART exposure impairs differentiation and maturation of hematopoietic stem and progenitor cells (HSPCs). Bone marrow will be analyzed via flow cytometry, differentiation assays, and single-cell RNA/ATAC-sequencing. Functional HSPC capacity will be tested via transplantation into immunodeficient mice. This study uses a clinically highly relevant primate model for HIV cure research and neonatal immunity, and advanced immunological tools to uncover how maternal HIV and LA-ART exposure alter infant immune development. Findings will guide future strategies to improve immune outcomes in HEU children. Project Number: 1R01HD121457-01 | Fiscal Year: 2026 | NIH Institute/Center: Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) | Principal Investigator: Oleg Varlamov (+1 co-PI) | Institution: OREGON HEALTH & SCIENCE UNIVERSITY, PORTLAND, OR | Award Amount: $2,720,461 | Activity Code: R01 | Study Section: Special Emphasis Panel[ZRG1 EMS-E (55)] View on NIH RePORTER: https://reporter.nih.gov/project-details/11327880