Genotypic and phenotypic evidence of different drug-resistance mutation patterns between B and non-B subtype isolates of human immunodeficiency virustype 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 inhib itors (PI). Proviral and plasma viral pol gene fragment were amplified, seq uenced and subtyped. Nine samples clustered with protease subtype B referen ce strains and the remaining samples were classified as non-B subtype corre sponding 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 p resent the L90M and I84V mutations and used mainly G48V and V82A/F to achie ve drug resistance. A strong cross-resistance phenotype among all four PI w as associated with the mutation L90M in the subtype-B isolates, and with G4 8V and V82A \F in the non-B counterparts. This observation revealed that th e non-B viruses tested had specific genotypic characteristics contrasting w ith the subtype-B isolates.