Reduction in human immunodeficiency virus type 1 mutations associated withdrug resistance after initiating new therapeutic regimens in pretreated patients

The objective of this study was to investigate the effect of initiating a s alvage-therapy regimen on resistant viruses in heavily treated patients inf ected with human immunodeficiency virus type 1 (HIV-1), Nineteen patients r eceiving multiple antiretroviral drugs were tested for HIV-1 mutations asso ciated with drug resistance by using an in-house method at baseline and at weeks 2, 4, and 8 of the salvage-therapy regimen. For the majority of mutat ions analyzed, the mean number of detectable mutations at baseline was sign ificantly higher than the mean at weeks 2, 4, and 8 of salvage therapy. Int roducing new and more potent therapy reduces the number of detectable drug resistance-associated mutations within 8 weeks, and no evidence was found t hat the new therapy promoted the emergence of novel mutations.