Genotypic and Phenotypic Evidence of Different Drug-Resistance Mutation Patterns between B and Non-B Subtype Isolates of Human Immunodeficiency Virus Type 1 found in Brazilian Patients Failing HAART

We have investigated the phenotypic and genotypic susceptibility of 14 HIV-1 strains isolated from individuals failing HAART therapy to protease inhibitors (PI). Proviral and plasma viral pol gene fragment were amplified, sequenced and subtyped. Nine samples clustered with protease subtype B reference strains and the remaining samples were classified as non-B subtype corresponding to subtype F (n=4) and subtype A (n=1). Although all patients were treated with similar PI drug regimen, the non-B subtype isolates did not present the L90M and I84V mutations and used mainly G48V and V82A/F to achieve drug resistance. A strong cross-resistance phenotype among all four PI was associated with the mutation L90M in the subtype-B isolates, and with G48V and V82A/F in the non-B counterparts. This observation revealed that the non-B viruses tested had specific genotypic characteristics contrasting with the subtype-B isolates.