Testing for HIV-1 Drug Resistance

Viral resistance to antiretroviral agents may limit the efficacy of current treatment regimens for HIV-1 infection. The mutational patterns underlying resistance to each antiretroviral agent are often quite diverse, and cross-resistance patterns in each of the currently available classes are complex. Current methods for determining drug resistance include genotypic and phenotypic assays, and each has advantages and limitations. Prospective clinical trials assessing the utility of HIV-1 drug resistance testing have shown significant but modest improvement in virologic outcomes with genotypic assays. Some, but not all, trials of phenotypic resistance testing have demonstrated improved virologic outcomes. Resistance testing is currently recommended for patients who have virologie failure or have no response to an antiretroviral regimen, and for pregnant women. Testing should also be considered in treatment-naive patients in areas of high prevalence of transmitted drug-resistant virus.