Mechanisms of in vivo protection from HIV infection

DESCRIPTION (provided by applicant): We propose to develop and evaluate as a "proof-of-concept" two therapeutic approaches designed to augment the immune response of HIV-infected individuals. First, we will evaluate the effectiveness of augmenting HIV-1-specific immunity in HIV-1-infected individuals by transducing their CD34+ hematopoietic stem cells (HSC) or CD8+ T lymphocytes with a cocktail of lentiviral vectors encoding various HIV-1-specific TCRs restricted to the recipient's Class I HLA that will induce differentiation into effective HIV-1-specific CTLs after autologous transplantation. Specifically we will examine whether functional HIV-specific CD8+ CTLs can be generated by delivering genes encoding the alpha and beta chain of TCRs derived from potent HIV-specific CTLs into CD34+ HSC or CD8+ T lymphocytes. To this end we will characterize the in vitro and in vivo function of human HIV-specific CTLs, clone out the TCR alpha and beta chain cDNA from the most potent HIV-specific CD8+ CTL clones and insert them into novel lentiviral vectors. We will then determine the capacity of these vectors to introduce the cloned TCR genes into human hematopoietic precursor cells or CD8+ lymphocytes and program them to differentiate into HIV-specific CD8+ CTLs that display the in vitro and in vivo capacity to recognize and eliminate HIV-infected cells. Second, we will examine the relevance to HIV immunity of the recent finding that blocking the PD-1/PD-L1 inhibitory pathway restores functional activity to "exhausted" LCMV-specific CTLs. We propose to achieve this goal via closely related and coordinated aims: 1 )To evaluate the capacity of lentiviral vectors encoding TCR alpha and beta chains derived from potent human HIV-1-specific CTLs to generate functional human HIV-specific CTL after transduction of human CD8+ lymphocytes, 2) To determine whether lentiviral vectors expressing HIV- specific TCR alpha and beta chains can program human CD34+ HSC to differentiate into functional HIV- specific CTLs, and 3) To investigate whether blockade of the PD1/PD-L1 inhibitory pathway by treatment with Fc-PD1 or lg-PD1 fusion proteins increases the in vitro and in vivo function of HIV-specific CTLs. These approaches provide new modalities for increasing HIV-specific immunity by redirecting the immune response to produce CTLs that recognize immunoprotective epitopes and by blocking activation of PD-1, an inhibitory molecule expressed by activated CTL, enhances the function of HIV-specific CTLs.