Sequence diversity of the reverse transcriptase of human immunodeficiency virus type 1 from untreated Brazilian individuals

The presence of human immunodeficiency virus type 1 (HIV-1) bearing mutatio ns resistant to nucleosidic inhibitors of the viral reverse transcriptase ( RT) derived from HIV-seropositive asymptomatic and untreated volunteer bloo d donors was examined. The RT amplicons of 32 specimens were analyzed by us ing a reverse hybridization line probe assay technique that detects resista nce against zidovudine (3'-azido-3'-deoxythymidine [AZT], didanosine (2',3' dideoxyinosine [ddI], zalcitabine (2',3'-dideoxycytidine [ddC]), and lamiv udine ((-)-beta-L-2',3'-dideoxy-3'-thiacytidine [3TC]) at amino acid positi ons 41, 69, 70, 74, 184, and 215 of the HIV RT, One sample (brp004, subtype B) showed an AZT resistance secondary mutation at position K70R, Fifteen s pecimens revealed one or more sites of nonreactivity to both wild-type- and mutant-specific probes (dual nonreactivity), Samples were also submitted t o RT direct sequencing and phylogenetic analysis. Nine of 32 specimens belo nged to non-B subtypes (C, D, F, and F/B or B/F mosaics). Three of these no n-B isolates, named brp004, brp063, and brp069, revealed three other releva nt AZT resistance mutations-a T215F mutation and two M41L mutations, respec tively-hidden by the nonreactivity to line probe assay strips on the respec tive codon regions. The isolate brp004 also carried a D67N AZT resistance m utation revealed by direct sequencing. No nonnucleosidic RT inhibitor-resis tant mutation was found. The analysis revealed a frequency of 2.26 x 10(-4) mutations per nucleotide for independent samples related to RT resistance, These findings emphasize the magnitude of naturally occurring reservoirs o f drug-resistant virus among untreated HIV-1-positive individuals in Brazil .