Prevalence of HIV-1 drug resistance in antiretroviral-naive patients: a prospective study

The development of decreased viral susceptibility to one or more of the antiretroviral agents used in the combination treatment of HIV-1-infected patients frequently causes failure to achieve or maintain complete suppression of the virus. A decrease in antiretroviral drug susceptibility may develop during the course of therapy through the accumulation of resistance-associated mutations. Alternatively, an individual may become infected with a virus that already harbours mutations conferring decreased susceptibility to nucleoside reverse transcriptase inhibitors (NRTI), non-nucleoside reverse transcriptase inhibitors (NNRTI), or protease inhibitors (PI). Therapeutic options for such newly infected patients may be limited as a consequence. Although transmission of virus with decreased susceptibility to each of the three classes of drugs has been demonstrated, only limited and mainly retrospective data on the frequency of drug resistance in newly infected patients is available. Two prospective studies analysed the results of 81 and 57 patients, respectively. We report here the detailed results of a prospective study performed on 230 antiretroviral-naive HIV-1-infected patients from the USA. Both the genetic sequence and the phenotypic drug susceptibility profiles of the patient HIV-1 isolates were studied.