The rationale for a study on HIV-1 reverse transcriptase mutations and outcome of antiretroviral therapy with two nucleoside analogs

The development of resistance to antiretroviral drugs has been recognized a s an important cause of treatment failure in HIV-l-infected patients; howev er the correlation between emergence of resistance and treatment failure ha s not been yet clearly defined. The high rate of viral replication, togethe r with the lack of proof reading activity of HIV-1 reverse transcriptase, a ccounts for the rapid establishment of extensive genotypic variation, resul ting in the emergence of viral mutants showing primary or secondary resista nce to antiretroviral drugs. In this regard, phenotyping and genotyping all ow the detection of drug resistance. Both tests have advantages and limitat ions compared to each other. The complete suppression of viral replication seems to be the best way to avoid occurrence of drug resistance, and viral loads below the limit of detection can be usually achieved by a combination of 3 antiretroviral drugs. In this scenario, the proportion of HIV-l-infec ted patients on dual therapy is still relevant in Italy. We believe that th e study of this subset of individuals is very important, as resistance to n ucleoside analogues may impair the outcome of a future triple therapy. In a ddition, this study could contribute to define the role of resistance assay s in the management of HIV1-infected patients.