Existence of Anti-retroviral Drug Resistant Viruses Among Drug Naïve HIV-1 Infected Blood Donors, Bangkok, Thailand

Antiretroviral (ARV) drugs resistance due to viral gene mutations has been observed in all stages of human immunodeficiency virus type 1 (HIV-1) infection and represents a major obstacle to the success of HIV therapy. About 2-27% of primary HIV-1 infected individuals who have never been treated with ARV drug carried ARV drug resistant viruses. It is unknown if such drug resistance exists among recent HIV-1 infected Thais or not. This study proposed to determine the genotypic evidence of resistance-conferring HIV-1 mutants to ARV drug in the newly infected individual in Thailand. Plasma samples collected from 49 HIV-1 infected blood donors in Bangkok during 1995-2001 were examined for the presence of viral gene mutations in reverse transcriptase (RT) and protease region (PR). Among 43 samples (87.8%) which could be analysed for viral gene mutations, 2 samples (4.6%) contained viruses harboring primary mutation in RT region at positions M41L and T215Y/S which corresponded to the resistance of nucleoside reverse transcriptase inhibitors (NRTIs). Moreover, 18 samples (42%) contained viruses harboring one or more secondary mutations associated with ARV drug resistance. This study reported prevalence of ARV drug resistance of 4.6% (95%CI; 0.56-16.79%) among drug naive HIV-1 infected Thai blood donors. Further study is suggested to verify the impact on the long-term effect of these pre-existing ARV drug resistance mutations on HIV/AIDS therapy in Thailand. Keywords : ARV drug resistance, drug-na i ve, Thai blood donors