Cocktails of antiretroviral drugs (ART) have been successful in reducing viremia to undetectable levels in HIV+ adult subjects who have access to them and who can remain adherent. Yet, the suppressive drugs are unable to eliminate latent virus in cellular and tissue compartments and are thus required for continued remission. While ART is the standard of care for HIV+ mothers and their infants who are exposed to infection risk before, during, and after birth, it has not been possible to test the impact on viral reservoirs upon treatment interruption. We have developed a robust, reproducible nonhuman primate (NHP) model for transmission in utero, peripartum and breastfeeding, in order to examine new therapeutic regimens for pre-exposure prophylaxis (PrEP) or post-exposure prophylaxis (PEP). Passively transferred bNAbs can provide sterilizing immunity when used as PrEP in nonhuman primate models, and have also been recently shown to prevent the establishment of viral reservoirs when given as PEP within days of viral exposure. Studies designed to understand the mechanism of action of antibodies is a critical next step. The central hypothesis of this research proposal is that novel, orthogonal therapeutic treatment with ART, a CCR5-blocking antibody, and potent neutralizing human monoclonal antibodies (bNAbs) will result in highly controlled viremia and undetectable viral reservoirs in babies born to HIV-infected mothers. Newborn and infant rhesus macaques when infected orally with SHIVSF162P3 develop widely dispersed and rapidly diverging viral quasispecies in blood and tissues within the first few days to weeks of infection, resulting in high and persistent viremia. However, in newborn macaques that receive ART or bNAbs at 24-30 hours after exposure, permanent viral seeding is prevented, but delays in treatment result in rebound upon treatment cessation. The project will explore the effects of combination and sequential treatment with ART, Leronlimab, and bNAbs, which we predict will result in prevention of viral reservoir establishment when used as PrEP, and in reduction or elimination of viral reservoirs when used as PEP in the first few weeks after virus exposure. We will show the effects of reduced infectious centers by in vivo imaging with positron emission tomography and compare these results with standard virological assays and RNAscope imaging. Ulimately, we hope that this combination therapy will lead to translation into the clinic so that HIV-exposed and vertically infected babies can be treated for limited periods of time and experience durable viral remission without further treatment.

Public Health Relevance

The proposed work will test entirely novel approaches to achieve HIV-1 remission in infants and children affected by the global HIV-1 pandemic. A proven animal model of vertical HIV-1 infection in primates will be used to study a novel combined treatment of drugs, infection-blocking antibodies, and HIV-directed antibodies with the potential to reduce disease severity or clear infection, so that children will not need lifelong treatment. These clinical strategies could be adapted for addressing pediatric HIV-1 infection worldwide.

National Institute of Health (NIH)
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Research Project (R01)
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HIV Immunopathogenesis and Vaccine Development Study Section (HIVD)
Program Officer
Lorenzo, Eric
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Oregon Health and Science University
Schools of Medicine
United States
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Hessell, Ann J; Malherbe, Delphine C; Haigwood, Nancy L (2018) Passive and active antibody studies in primates to inform HIV vaccines. Expert Rev Vaccines 17:127-144
Pegu, Amarendra; Hessell, Ann J; Mascola, John R et al. (2017) Use of broadly neutralizing antibodies for HIV-1 prevention. Immunol Rev 275:296-312
Hessell, Ann J; Jaworski, J Pablo; Epson, Erin et al. (2016) Early short-term treatment with neutralizing human monoclonal antibodies halts SHIV infection in infant macaques. Nat Med 22:362-8