Update on Genotype-Guided Antiretroviral Therapy

Drug resistance is either the cause or the inevitable consequence of treatment falilure. HIV genotyping is now recommended to select the best antiretroviral therapy in a given patient in selected situations, but the benefit is greatly dependent of adequate interpretation and of the number of drugs for which sensitivity is apparently preserved. Information available support the use of drug resistance testing in subjects not exposed to antiretroviral agents in at least four situations: HIV-infected pregnant women, children born and infected from treated mothers, individuals presenting with the acute retroviral syndrome or having seroconverted within the past year, and in the setting of post-exposure prophylaxis. Among pre-treated persons, drug resistance testing seems to be a particularly useful tool in subjects on early virologic failure. The benefit of drug resistance testing in naive individuals with chronic HIV infection or in heavily pretreated persons on failure is so far not well established. The reliability of testing subjects with non-B viruses or with low levels of viremia is under discussion. The search for new drug-resistant genotypes and the establishment of large databases pairing geno-phenotypes must be encouraged.