Prevalence of Etravirine Resistance Associated Mutations in HIV-1 Strains Isolated From Infected Individuals Failing Efavirenz: Comparison Between Subtype B and Non-B Genetic Variants

Service of Infectious Diseases, Coimbra University Hospitals, Coimbra, PortugalEtravirine (ETR) is a non-nucleoside analoguereverse transcriptase inhibitor (NNRTI) with ahigh genetic barrier to the development ofresistance and with potential activity againstHuman immunodeficiency virus type 1 (HIV-1)strains resistant to first-generation NNRTIs. Theobjective of this study was to investigate theprevalence of ETR resistance associated muta-tions (RAMs) in HIV-1 strains isolated frominfected individuals failing efavirenz (EFV), aswell as to evaluate possible differences in thedistribution of ETR RAMs between subtype Band non-B genetic variants. Nucleotide sequen-ces of the protease and partial reverse tran-scriptase (RT) coding regions of the pol gene of55 HIV-1 strains isolated from infected individu-als failing EFV on regular follow-up at a refer-ence center in Portugal, were retrospectivelyanalyzed. The most prevalent ETR RAMsobserved were L100I, V90I, and K101E, with aprevalence of 16.4% (n ¼ 9), 9.1% (n ¼ 5), and5.5% (n ¼ 3), respectively. Overall, 47.3%(n ¼ 26) of the nucleotide sequences had atleast one ETR RAM: 38.2% (n ¼ 21) had oneETR RAM, 7.3% (n ¼ 4) had two ETR RAMs and1.8% (n ¼ 1) had three ETR RAMs. No statisti-cally significant differences were found in thedistribution of ETR RAMs between subtype Band non-B genetic variants. The results demon-strate that ETR rescue therapy is a viable optionin treatment-experienced individuals failingEFV and suggests that ETR may be equallyuseful in HIV-1 infections caused by differentgenetic variants. J. Med. Virol. 84:551–554,2012.