Resistance to anti-retroviral therapy in Chilean patients with HIV-1 from 2002 to 2005

Resistance limits the effectiveness of anti-retroviral therapy. In Chile, there is free access to highly active anti-retroviral therapy since 2001, but there is no information about the frequency of mutations associated to drug resistance. To determine the most common mutations associated to anti-retroviral drug resistance in Chile. Retrospective study of 710 genotype analysis coming from 568 patients aged 22 to 70 years (85% males) with virological failure. The analysis was performed using a commercially available sequencing kit (Trugene HIV-1 genotypic assay from Bayer S.A). Mean CD4(+) cell count and viral load were 154 cells/microl and 228784 RNA copies/ml, respectively. The frequency of resistance to nucleoside RT inhibitors (NRTI), non nucleoside RT inhibitors (NNRTI) and protease inhibitors (PI) was 71 %, 62% and 22%, respectively. The most common mutations found were T215Y (46%), L10F (44%), Ml84V (3896), K103N (35%) and M41L (32%). Fifty five percent of mutations corresponded to the TAM (thymidine analogue mutations) group. Multiresistance was 47% to NNRTI, 7% to NRTI, 4% to PI and 0.7% to all groups. During the four years of the study, there was a significant increase in NNRTI resistance. These data provides important information about the epidemiology of drug resistance mutations and should help to design new HAART strategies.