427. In Vivo Inhibition of HIV-1 in NSG Mice After Transduction of Primary Human T Cells with CXCR4 Conjugated to an HR2 Peptide

Introduction: We previously reported that a 34 a.a. peptide from the C-terminal heptad repeat-2 domain (HR2) of HIV-1 gp41 (C34) when fused to the N-terminus of CXCR4 (C34-X4) inhibits HIV-1 infection in transduced cells in vitro. This construct provided protection irrespective of HIV viral tropism (i.e., C34-X4 could inhibit R5, X4 or dual-tropic isolates).Methods: To assess the ability of C34-conjugated coreceptor to exert transdominant inhibition of R5- and X4-tropic HIV-1 in vivo, C34-X4 was transduced using a lentiviral vector into CD3/CD28-stimulated primary human CD4+ T cells with GFP-transduced T cells serving as a control. Cells were infused in NOD-scid-gamma (NSG) mice either undiluted or mixed (25% of total cells) with untransduced T cells. After 21 days, mice were challenged i.v. with R5 (US1, Clade B) and X4 (CMU02 Clade A/E) tropic HIV-1 and infection assessed by plasma viral RNA levels and by survival of C34-X4-expressing cells.Results: In NSG mice receiving C34-X4 transduced cells, at Day 18 there was significant expansion of the CD4+/CD45+/CXCR4+ T cell population, but not of GFP control cells (p=0.005). Viral loads were significantly lower in mice receiving C34-X4 transduced cells compared to those receiving GFP-transduced cells (p=0.047). At necropsy (Day 28) in splenocytes there was an approximate 2 log increase in the number of CD4 T cells in mice receiving C34-X4 transduced cells (p=0.001).Conclusion: These studies demonstrate that the C34 peptide conjugated CXCR4 confers resistance of CD4 T cells to HIV-1 infection irrespective of viral tropism, providing a proof of concept that targeting an HR2 inhibitory peptide to a coreceptor exerts potent transdominant inhibition of HIV-1 in vivo. This novel genetic approach to confer HIV resistance to CD4 T cells, coupled with high barriers for viral resistance to C34-coreceptors, may provide a novel approach for HIV control in humans.