Genotypic Resistance Mutations in Treatment-Naïve and Treatment-Experienced Patients under Widespread Use of Antiretroviral Drugs in Thailand: Implications for Further Epidemiologic Surveillance

The aims of this study were to illustrate the prevalence and determinants of mutations associated with antiretroviral drug resistance in a group of antiretroviral-naïve and treatment-experienced patients in Thailand, where antiretroviral drugs are widely used. One hundred and thirteen treatment-naïve (92 CRF01_AE and 21 subtype B patients) and 1,709 treatment-experienced patients were recruited. Genotypic resistance to antiretroviral drugs was studied by sequencing the isolated viruses. Mutation frequencies in treatment-naïve patients were reported along with those for treatment-experienced patients. The results showed that all of the patients with treatment experience showed the same pattern of genotypic resistance. The results also showed that only 14 drug-naïve patients (12.4%) carried HIV-1, with at least one drug-resistant mutation. Moreover, four drug-naïve patients were found to carry the marker mutations for transmission of drug resistance. The most commonly found marker in drug-naïve patients was M36I/V/L (n = 90, 81.1%), which is a common natural polymorphism among HIV-1 subtype CRF01_AE individuals. In order to prevent the rapid emergence of resistant virus strains, a national program to monitor antiretroviral drug resistance should be established. We also recommend routine genotypic testing in treatment-naïve patients before starting antiretroviral therapy to prevent subtherapeutic response and viral failure.