More than 200 mutations are associated with antiretroviral resistance to drugs belonging to six licensed
antiretroviral classes. More than 50 reverse transcriptase mutations are associated with nucleoside
reverse transcriptase inhibitor resistance including M184V, thymidine analog mutations, mutations
associated with non-thymidine analog containing regimens, multi-nucleoside resistance mutations, and
several recently identified accessory mutations. More than 40 reverse transcriptase mutations are
associated with nonnucleoside reverse transcriptase inhibitor resistance including major primary
and secondary mutations, non-polymorphic minor mutations, and polymorphic accessory mutations.
More than 60 mutations are associated with protease inhibitor resistance including major protease,
accessory protease, and protease cleavage site mutations. More than 30 integrase mutations are
associated with the licensed integrase inhibitor raltegravir and the investigational inhibitor elvitegravir.
More than 15 gp41 mutations are associated with the fusion inhibitor enfuvirtide. CCR5 inhibitor
resistance results from mutations that promote gp120 binding to an inhibitor-bound CCR5 receptor or
CXCR4 tropism; however, the genotypic correlates of these processes are not yet well characterized.