Mapping the determinants in owl monkey CD4 and CCR5 that allow entry of early-stage HIV-1 Env variants

Thesis (Master's)--University of Washington, 2016-06

Many physiological and immunological aspects of non-human primates make them ideal candidates for animal models of HIV-1 transmission and vaccine studies. However, HIV-1 does not infect most non-human primates because of species-specific host restriction factors and/or inability of the receptor for HIV-1, the CD4 proteins, to function efficiently as HIV-1 receptors for viral entry. This study aimed to determine if owl monkey species encode CD4 receptors and CCR5 coreceptors that support cellular entry by variants representing transmitted, circulating forms of HIV-1. The functionality of owl monkey CD4s as receptors and CCR5s as coreceptors was evaluated using infectivity assays with HIV-1 pseudotyped with envelope protein. Here, we have identified owl monkey CD4s that naturally function as receptors for HIV-1 entry and our data corroborate previous findings that N39 in the D1 domain of CD4 is important for usage as a receptor by transmitted HIV-1 envelope variants. Additionally, we have mapped residues in CCR5 necessary for transmitted HIV-1 envelope variant entry into cells. Two amino acid residues in CCR5, Y15 and T16, were found to be sufficient to support HIV-1 entry into cells for some, but not all, envelope variants tested. This research will assist in identifying new non-human primate models of HIV-1 infection that can support replication of transmitted forms of HIV-1 variants (and/or SHIVs) that are relevant for vaccine and therapeutic approaches.