Abstract:
As of the year 2004, there were approximately 1 million people infected with HIV-1 in Thailand with 19,500 new infections. Recently, the Thai government has a policy that all HIV-1 infected individuals must be able to access antiretroviral drugs. The increased availability of the drugs may change the drug resistance mutation pattern of HIV-1 among infected people in Thailand. At present, the frequency of antiretroviral drug resistance in Thailand has not been well characterized. Therefore, this study aims to identify the drug resistance mutation pattern of HIV-1 among GPOVIR treated Thai patients. EDTA blood from 74 subjects were used for detection of mutations in the HIV-1 pol gene by nucleotide sequencing and determination of HIV-1 plasma viral quantitation before changing the anti-retroviral treatment regimen. After that, HIV-1 viral quantification was used to monitor the efficacy of new drug regimens every 3 months. The level of HIV-1 viral load reduction in subjects group who received drug formula 1 (LPV/RTV+SQV) was compared with those of drug formula 2 (NRTI+IDV/RTV) group. There were no statistically significant differences (p > 0.05) between viral load decrease of the 2 groups at every time point. Reverse transcriptase inhibitor related resistant codons were found in 62 subjects. The frequent Nucleoside Analogue Reverse Transcriptase Inhibitors (NRTI) drug resistant codon mutations were M184I/V (15.38%), D67N (13.85%), T215F/Y (10%) and Non-Nucleoside Analogue Reverse Transcriptase Inhibitors (NNRTI) drug resistant codon mutations were G190A/S (21.49%), Y181C (20.66%), K103N/S (18.18%). There was M184V and Y181C substitution in the RT coding sequencing in samples from subjects who received GPO-VIR before changing drug regimen. There was no amino acid substitution at these positions in samples from those who received NRTIs other than drugs in GPO-VIR and one drug of NNRTI. Of 260 NRTI drug resistant codon mutations, 150 (57.69%) were thymidine analogue mutations (TAMs) including M41L (8.46%), E44D (2.31%), D67N (13.85%), K70R (8.85%), L210W (6.92%), T215Y/F (10%), K219E/Q (7.31%). The frequency of co-presence of M184V/I and TAMs was 82.5%. Analysis of drug resistance mutation codons and viral load response after changing to a new drug regimen showed no association with number of codon mutations on viral response. These findings might provide valuable information that could guide the modification of regimen and treatment strategies.