Antiretroviral resistance during successful therapy of HIV type 1 infection

HIV type 1 (HIV-1) drug resistance mutations were selected during antiretro viral therapy successfully suppressing plasma HIV-1 RNA to <50 copies/ml. N ew resistant mutant subpopulations were identified by clonal sequencing ana lyses of viruses cultured from blood cells. Drug susceptibility tests showe d that biological clones of virus with the mutations acquired during succes sful therapy had increased resistance. Each of the five subjects with new r esistant mutants had evidence of some residual virus replication during hig hly active antiretroviral therapy (HAART). based on transient episodes of p lasma HIV-1 RNA > 50 copies/ml and virus env gene sequence changes. Each ha d received a suboptimal regimen before starting HAART. Antiretroviral-resis tant HIV-1 can be selected from residual virus replication during HAART in the absence of sustained rebound of plasma HIV-1 RNA.