Clonal expansion of genome-intact HIV-1 in functionally polarized Th1 [CD4.sup.+] T cells

HIV-1 causes a chronic, incurable disease due to its persistence in [CD4.sup.+]T cells that contain replication -competent provirus, but exhibit little or no active viral gene expression and effectively resist combination antiretroviral therapy (cART). These latently infected T cells represent an extremely small proportion of all circulating [CD.sup.+]T cells but possess a remarkable long-term stability and typically persist throughout life, for reasons that are not fully understood. Here we performed massive single-genome, near-full-length next-generation sequencing of HIV-1 DNA derived from unfractionated peripheral blood mononuclear cells, exvivo-isolated [CD4.sup.+]T cells, and subsets of functionally polarized memory [CD4.sup.+]T cells. This approach identified multiple sets of independent, near-full-length proviral sequences from cART-treated individuals that were completely identical, consistent with clonal expansion of [CD4.sup.+]T cells harboring intact HIV-1. Intact, near-full-genome HIV-1 DNA sequences that were derived from such donally expanded [CD4.sup.+] T cells constituted 62% of all analyzed genomeintact sequences in memory [CD4.sup.+] T cells, were preferentially observed in Th1-polarized cells, were longitudinally detected overa duration of up to 5 years, and were fully replication- and infection-competent. Together, these data suggest that clonal proliferation of Th1-polarized [CD4.sup.+]T cells encoding for intact HIV-1 represents a driving force for stabilizing the pool of latently infected [CD4.sup.+]T cells.