Human immunodeficiency virus type 1 quasi species that rebound after discontinuation of highly active antiretroviral therapy are similar to the viralquasi species present before initiation of therapy

In an effort to identify the sources of the viruses that emerge after disco ntinuation of therapy, analyses of human immunodeficiency virus (HIV) quasi species were done for 3 patients with sustained levels of HIV RNA of <50 c opies/mL for 1-3 years. The sequences found in the rebounding plasma virus were closely related to those of the actively replicating form of viruses p resent before the initiation of combination therapy. All quasi species foun d in the rebounding plasma virus were also present in proviral DNA, cell-as sociated RNA in peripheral blood mononuclear cells (PBMC), and virion RNA d erived from PBMC coculture during periods when plasma HIV RNA levels were < 50 copies/mL. These findings suggest that the rapid resurgence of plasma vi remia observed after discontinuation of therapy and the viruses cocultured from PBMC are derived from a relatively stable pool of the replicating form of virus rather than from activation of a previously latent pool.