ESTABLISHMENT AND REVERSAL OF HIV-1 LATENCY IN PRIMARY CD4+ NAIVE AND CENTRAL MEMORY T CELLS

Human immunodeficiency virus type 1 (HIV-1) persists as a lifelong infection, due to the establishment of a latent viral reservoir in rCD4+ T cells, representing a major barrier to eradication of HIV-1 infection. Therapeutic approaches to eliminate this latent reservoir have included the “kick and kill” strategy, which involves the administration of a latency reversing agent (LRA) to “kick” HIV-1 out of latency and “kill” the HIV-1-infected cells by cytolytic or viral cytopathic effects. rCD4+ T cells are heterogeneous, consisting of naïve (TN), stem cell-like memory (TSCM), central memory (TCM), transitional memory (TTM), effector memory (TEM), and terminally differentiated (TTD) cells. Preliminary studies demonstrated that the TCM and TTM cell subsets constitute the major proportion of the latent HIV-1 reservoir in infected individuals on ART, while HIV-1 DNA is consistently lower in TN cells. Consequently, there has been little emphasis on studying HIV-1 latency in TN cells. The primary goal of this thesis was to understand latent HIV-1 infection in TN cells in comparison to TCM cells, through the development of an appropriate in vitro primary cell model of HIV-1 latency in TN and TCM cells, as well as in ex vivo patient-derived cells. Employing the “kick and kill” approach to TN and TCM cells in our in vitro primary cell model revealed that although TN cells contained significantly less HIV-1 DNA than TCM cells, following reactivation, they produced as much, if not more, virus than TCM cells when normalized for infection frequency. This finding was also observed using ex vivo cells from 4 of 7 donors. Furthermore, we found that similar levels of replication-competent virus were recovered from TN and TCM cells when corrected for infection frequency. These findings suggest that quantifying HIV-1 DNA alone may not be predictive of the size of the inducible latent reservoir in different CD4+ T cell subsets. Furthermore, although TN cells constitute only a fraction of the HIV-1 DNA reservoir, they may contribute significantly to viral rebound following treatment interruption or failure. Thus, a greater attention should be given to the latent viral reservoir in TN cells in HIV-1-infected individuals on ART