HIV resistance to antiviral therapy

::Antiretroviral compounds can select viral strains presenting mutations of the HIV genome. Certain genotypic modifications are expressed by phenotypi c resistance There is no cross resistance between different classes of comp ounds (nucleosides, non nucleosides, antiproteases), but cross resistance i s common within a given therapeutic class, HIV resistance to antiretroviral compounds is one of the principal causes of failure of antiretroviral trea tments but cannot explain all escapes. The number of resistance mutations i s higher,in patients with high viral loads and in patients on multiple drug regimens. Currently resistance testing is limited to clinical research pro tocols. The usefulness of resistance testing remains to be validated. Howev er the most eminent indications are epidemiological surveillance of primary resistance in primary infections, therapeutic: adaptation after accidental exposure to HIV, and management of seropositive pregnant women. Recent ret rospective studies have shown that the genotype and the phenotype after a f irst line treatment failure predict response to certain therapeutic combina tions. In the near future, resistance testing could be useful to adapt anti viral strategies after earlier treatment failure.