Brazilian Network for HIV Drug Resistance Surveillance (HIV-BResNet): a survey of chronically infected individuals

To study the prevalence of HIV drug resistance mutations and subtype distribution in a Brazilian drug-naive population. Asymptomatic, drug-naive HIV-1-infected individuals were targeted in 13 voluntary counseling and testing centers spread around the country.

Plasma viral RNA was extracted from 535 HIV-1-positive subjects. Protease (PR) and reverse transcriptase (RT) genomic regions were sequenced for subtype determination and analysis of drug resistance mutations.

Eight samples (2.24 %) showed primary mutations related to protease inhibitor (PI) resistance, eight (2.36%) to nucleoside reverse transcriptase inhibitors (NRTI) and seven (2.06%) to non-nucleoside reverse transcriptase inhibitors (NNRTI). Accessory mutations were found in the PR gene at the following positions: L63P/V/T/A/I [153/345 (44.3%)], M36I/L [149/345 (43.2%)], L10I/F/V [82/345 (23.8%)], V77I [60/345 (17.4%)], A71V/T [11/345 (3.2%)], K20M/R [10/345 (2.9%)], and V82I [4/345 (1.2%)]. Mutations known to be associated with reduced sensitivity to NRTI or NNRTI (V118I, E44D, K219R, T69A, and V75L) were found in a low prevalence (0.6-2.4%). A high proportion of the isolates from subtype C was found in the southern states. Subtype F-related viruses were the main non-B variant in the rest of the country.

Brazil has a low prevalence of drug-resistant strains circulating among recently diagnosed individuals. However, there was an increase in these rates compared with similar studies performed with samples collected in Brazil from 1996 to 1998. Continued surveys are required to detect trends in these rates, but routine genotypic testing in the drug-naive population prior to antiretroviral initiation is not required in Brazil.