A study of seven rule-based algorithms for the interpretation of HIV-1 genotypic resistance data in Thailand.

Since the free therapy program was started by the Thai government, the number of patients infected by HIV-1 with access to antiretroviral drugs has increased. The selection of effective interpretation algorithms for antiretroviral drug resistance has become even more important for clinical management. In this retrospective study, the level of agreement was evaluated in 721 antiretroviral-therapy failing HIV-1 subjects. Regarding genetic diversity, about 89% was recognized as non-B variants (CRF01_AE). The level of complete concordant interpretation score in all seven algorithms was recognized in non-nucleoside reverse transcriptase inhibitors (NNRTIs) and protease inhibitors (PIs) (67%), but not in nucleoside reverse transcriptase inhibitors (NRTIs) (52%). Over 10% of the major discordance score with TRUGENE was revealed in didanosine (Agence Nationale de Recherches sur le SIDA[ANRS]; Detroit Medical Centre [DMC]), abacavir (ANRS; Centre Hospitalier de Luxembourg [CHL]), and also with delavirdine, indinavir and amprenavir (Grupo de Aconselhamento Virológico [GAV]). A good to excellent agreement range of kappa scores was detected for most antiretroviral drugs. However, poor agreement with the TRUGENE system (k<0.40) was seen in the ANRS system with didanosine, abacavir and lopinavir; GAV system in indinavir and amprenavir; and DMC system in ritonavir. These might be an option for resource limited countries when selecting the use of a low cost or free algorithm interpretation, which has excellent agreement as the U.S. Food and Drug Administration (FDA)-approved TRUGENE commercial system.

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-naive and treatment-experienced patients in Thailand, where antiretroviral drugs are widely used. One hundred and thirteen treatment-naive (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-naive patients were reported along with those for treatment-experienced patients. The results showed that all of the patients with treatment-experienced patients showed the same pattern of genotypic resistance. The results also showed that only 14 drug-naive patients (12.4%) carried HIV-1, with at least one drug-resistant mutation. Moreover, four drug-naive patients were found to carry the marker mutations for transmission of drug resistance. The most commonly found marker in drug-naive 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-naive patients before starting antiretroviral therapy to prevent subtherapeutic response and viral failure.

Prevalence of genotypic HIV-1 drug resistance in Thailand, 2002.

BACKGROUND: The prices of reverse transcriptase (RT) inhibitors in Thailand have been reduced since December 1, 2001. It is expected that reduction in the price of these inhibitors may influence the drug resistance mutation pattern of HIV-1 among infected people. This study reports the frequency of HIV-1 genetic mutation associated with drug resistance in antiretroviral-treated patients from Thailand. METHODS: Genotypic resistance testing was performed on samples collected in 2002 from 88 HIV-1 infected individuals. Automated DNA sequencing was used to genotype the HIV-1 polymerase gene isolated from patients' plasma. RESULTS: Resistance to protease inhibitors, nucleoside and non-nucleoside reverse transcriptase inhibitors were found in 10 (12%), 42 (48%) and 19 (21%) patients, respectively. The most common drug resistance mutations in the protease gene were at codon 82 (8%), 90 (7%) and 54 (6%), whereas resistant mutations at codon 215 (45%), 67 (40%), 41 (38%) and 184 (27%) were commonly found in the RT gene. This finding indicates that genotypic resistance to nucleoside reverse transcriptase inhibitors was prevalent in 2002. The frequency of resistant mutations corresponding to non-nucleoside reverse transcriptase inhibitors was three times higher-, while resistant mutation corresponding to protease inhibitors was two times lower than those frequencies determined in 2001. CONCLUSION: This study shows that the frequencies of RT inhibitor resistance mutations have been increased after the reduction in the price of RT inhibitors since December 2001. We believe that this was an important factor that influenced the mutation patterns of HIV-1 protease and RT genes in Thailand.

Prevalence of HIV-1 polymerase gene mutations in pre-treated patients in Thailand.

To determine the prevalence of drug resistance-conferring mutations in human immunodeficiency virus type 1 (HIV-1), 83 HIV-1 infected Thai patients who had been treated with any antiretroviral drug were studied. HIV-1 RNA was reverse transcribed and amplified by RT-PCR. The direct sequencing of HIV-1 reverse transcriptase (RT) and protease was then performed. Changes in nucleotide and amino acid sequences were determined by comparison with a pNL4-3 reference sequence. Data on mutations associated with resistance to antiretroviral drugs were obtained from literature. The mutations associated with lamivudine resistance (M184V/I) were found most often (in 45.7% of individuals). Zidovudine-resistant mutants: T215Y/F (36%), M41L (28%) and K70R (25.3%) were common; but mutations linked to didanosine (L74V) and multinucleoside-resistant genotypes (Q151M) were rarely recognized (2.4% and 3.6%, respectively). The stavudine-resistant mutant (V75T) and T69 insertions were not found. All subjects who had a significant exposure to antiretroviral drugs and current virological failure in the past carried drug-resistant genotypes. Genotypic resistance to zidovudine, lamivudine, zalcitabine, indinavir and ritonavir appeared in more than one third of the samples, which suggested that the prevalence of the HIV-1 resistance-conferring genotype resisting reverse transcriptase inhibitors and/or protease inhibitors was high in treatment experienced patients.