Genotypic evaluation of etravirine sensitivity of clinical human immunodeficiency virus type 1 (HIV-1) isolates carrying resistance mutations to nevirapine and efavirenz.

Background: Etravirine is a second-generation non-nucleoside reverse transcriptase inhibitor (NNRTI) with a pattern of resistance mutations quite distinct from the current NNRTIs.

Methods: We collected all routine samples of HIV-1 patients followed in the AIDS reference laboratory of UCLouvain (in 2006 and 2007) carrying resistance-associated mutations to nevirapine (NVP) or efavirenz (EFV). The sensitivity to Etravirine was estimated using three different drug resistance algorithms: ANRS (July 2008), IAS (December 2008) and Stanford (November 2008). We also verified whether the mutations described as resistance mutations are not due to virus polymorphisms by the study of 58 genotypes of NNRTI-naive patients.

Results: Sixty one samples harboured resistance to NVP and EFV: 41/61 had at least one resistance mutation to Etravirine according to ANRS-IAS algorithms; 42/61 samples had at least one resistance mutation to Etravirine according to the Stanford algorithm. 48 and 53 cases were fully sensitive to Etravirine according to ANRS-IAS and Stanford algorithms, respectively. Three cases harboured more than three mutations and presented a pattern of high-degree resistance to Etravirine according to ANRS-IAS algorithm, while one case harboured more than three mutations and presented high degree resistance to Etravirine according to the Stanford algorithm. The V1061 and V179D mutations were more frequent in the ARV-naive group than in the NNRTI-experienced one.

Conclusions: According to the currently available algorithms, Etravirine can still be used in the majority of patients with virus showing resistance to NVP and/or EFV, if a combination of other active drugs is included.