The prevalence and determinants of the K65R mutation in HIV-1 reverse transcriptase in tenofovir-naive patients.

The K65R mutation in HIV-1 reverse transcriptase is associated with reduced susceptibility to abacavir and tenofovir. We established its prevalence within a large clinical database, and investigated correlations with other resistance-associated mutations and antiretroviral history. The presence of K65R is associated with previous abacavir use. Although rare, it is preferentially selected within non-thymidine analogue-containing regimens, compared with concurrent zidovudine or stavudine use, which is associated with thymidine analogue mutations. Both genetic routes may compromise abacavir and tenofovir activity.