Pre-existing low-frequency resistance mutations increase the risk of antiretroviral treatment failure in HIV-1 naïve patients

To the Editor:High-frequency resistance(typically≥15-25%viral quasispecies)detected by conventional resistance assays has long been associated with failure of antiretroviral therapy(ART)to suppress viral replication,[1]but the impact of pre-existing lowfrequency resistance on virological response is controversial.Previous studies have shown an increased likelihood of virological response failure in patients with preexisting low-frequency resistance mutations after initiation of antiviral therapy,especially primary ART regimens containing non-nucleoside reverse transcriptase inhibitors(NNRTIs).[2]However,some studies have concluded differently,suggesting that pre-existing lowfrequency resistance mutations do not correlate with viral response failure.[3]This may be related to the method of detection of pre-existing low-frequency resistance mutations.