HIV persistence: clonal expansion of cells in the latent reservoir.

While antiretroviral therapy (ART) can reduce HIV-1 to undetectable levels, the virus generally reappears if treatment is stopped. Resurgence of the virus is due to the reactivation of T cells harboring latent integrated provirus, and recent studies indicate that proliferation of these latently infected cells helps maintain the HIV-1 reservoir. In this issue of the JCI, Lee et al. evaluated CD4+ T cell subsets to determine whether certain populations are more likely to harbor full-length, replication-competent provirus. The authors identified an enrichment of clonally expanded Th1 cells containing intact HIV-1 proviruses, suggesting that this polarized subset contributes to the persistence of the reservoir. Strategies to target these provirus-harboring cells need to be considered for future therapies aimed toward HIV-1 cure.