760. Overcoming Rhesus Macaque Endogenous Restriction Factors during HIV-1 Vector Transduction

Abstract

Top of pageAbstract The ability to deliver genes into hematopoietic stem cells via HIV-1 derived vectors holds promise to investigate the pathobiology and therapeutic applications for infectious diseases. In vivo HIV-1 infection models are limited. The NOD/SCID-hu mouse has been an excellent model to study thymic function and HIV-1 thymic depletion. However, to better understand HIV-1 pathogenesis in humans, non-human primate models must be used. The rhesus macaque simian immunodeficiency virus (SIV) model recapitulates aspects of the pathology seen in human HIV-1 infection. Our laboratory has designed and previously described a CCR5 intrabody HIV-1 vector that efficiently prevents R5-tropic HIV-1 entry and provides transduced CD4+ T cells with a selective advantage during a dendritic cell-mediated infection. Unfortunately, transduction with a HIV-1 derived vector undergoes a post-entry restriction when introduced into rhesus macaque cells. The target for rhesus macaque endogenous restriction factors lies within the HIV-1 capsid protein, and may be due to rhesus macaque Cyclophilin A (CypA) incorporation and TRIM-5|[alpha]| capsid interactions. To increase transduction efficacy in both non-human primate and human hematopoietic cells we have assessed a naturally occurring HIV-1 capsid motif (V86P/H87Q/I91V/M96I), which evades both CypA- dependence in human cells and TRIM-5|[alpha]|-CypA restriction in owl monkey kidney cells during HIV-1 infection (Chatterji, et al. JBC, 2005). The V86P/H87Q/I91V/M96I capsid mutation within the CypA binding loop also rendered VSV-G pseudotyped HIV-1 vectors independent of CypA incorporation during human and non-human primate cell transduction. Interestingly, HIV-1 vectors with the V86P/H87Q/I91V/M96I capsid mutation were able to efficiently transduce non-human primate Vero and sMAGI cell lines and yielded a 1.4-fold increase in transduction efficiency in primary human CD4+ T cells. However, the V86P/H87Q/I91V/M96I HIV-1 vector did not efficiently transduce primary rhesus macaque CD4+ T cells. We are now in the process of evaluating novel HIV-1 capsid mutations that lie within and around the CypA binding loop in our HIV-1 vector system, such as H87Q and Q50Y/T54Q. Some of these capsid mutations in HIV-1 are required to efficiently infect primary rhesus macaque macrophages. We will present our findings on HIV-1 capsid mutations that allow HIV-1 vector entry into primary rhesus macaque CD4+ T cells.