Minority HIV-1 Resistant Variants in Recent Infection and in Patients Who Failed First-Line Antiretroviral Therapy With No Detectable Resistance-Associated Mutations in Thailand

HIV-NAT, Thai Red Cross AIDS Research Center, Bangkok, ThailandThrough the Thai National AIDS Program,approximately 200,000 patients infected withHIV are on antiretroviral (ARV) therapy.Although studies have shown low prevalenceof primary HIV-1 resistance transmission inThailand and in Southeast Asia where subtypeCRF01_AE is predominant, minority HIV-1 drugresistance has not been studied. Two groupsof patients, whose conventional genotypingresults showed no drug resistance-associatedmutations, were investigated: 104 homosexualmen recently infected with HIV-1, nai¨ve to ARVtreatment and 22 first-line non-nucleosidereverse transcriptase inhibitor (NNRTI)-basedfailure patients. Pyrosequencing (PSQ) assaywas developed to detect and quantify minorityY181C and M184V variants from the patients’plasma samples. The sensitivity of PSQ to de-tect minority Y181C and M184V variants wasapproximately 1%. 1/104 (0.5%) and 3/101 (3%)samples were found harboring Y181C andM184V in the group of homosexual men re-cently infected with HIV-1. In patients withfirst-line treatment failure, one had a minorityM184V mutation (4.5%). The prevalence ofY181C and M184V minority variants in homo-sexual men recently infected and nai¨ve totreatment was low in Thailand. Systematicmonitoring of primary resistance transmis-sion in Thailand and this region is essentialto guide whether genotypic resistance testis required prior to commencing the first-line highly active antiretroviral therapy(HAART). J. Med. Virol. 84:713–720,2012.