title: Phenotypic susceptibility to antiretrovirals among clades C, F, and B/F recombinant antiretroviral-naive HIV type 1 strains.
abstract: To evaluate antiretroviral phenotypic susceptibility of wild-type HIV-1 strains circulating in Brazil, samples from antiretroviral-naive individuals infected with subtypes C (n=16), F (n=9), or B/F (n=7), where reverse transcriptase is B and protease is F, were phenotyped using the Antivirogram Assay (Virco, Mechelen, Belgium). Reduced susceptibility to protease inhibitors (PIs) was observed in one C and three F isolates. None of these samples had any known PI resistance mutations. The phenotypic fold change to one PI was above the biological cut-off in three of 96 (3.1%) clade F phenotypic determinations and in one of 96 (1.0%) clade C. Phenotypic resistance to at least one nucleoside reverse transcriptase inhibitor (NRTI) was found for two B/F, four C, and three F isolates. The phenotypic fold change in susceptibility to NRTIs was above the cut-off value in nine of 111 (8.1%) clade C determinations, as compared to three of 63 (4.8%) for clade F and two of 49 (4.1%) for clade B. The phenotypic fold change to non-NRTI (NNRTI) was above the cut-off in seven of 32 (21.9%) of C isolates determinations, whereas none of the F isolates had a decrease of susceptibility. Only two of the 16 C samples had a known NNRTI resistance mutation. The NNRTI fold change was above the cut-off value in three of 14 (21.4%) phenotypic determinations of Brazilian B/F recombinants, representing clade B reverse transcriptase. NNRTI susceptibility should be better investigated in clade C and B/F recombinants.
authors: Federal University of São Paulo, São Paulo, Brazil.
authors: Maria Cecilia A
authors: MC
authors: Sucupira
authors: Patricia
authors: P
authors: Munerato
authors: Jussara
authors: J
authors: Silveira
authors: André F
authors: AF
authors: Santos
authors: Luiz Mário
authors: LM
authors: Janini
authors: Marcelo A
authors: MA
authors: Soares
authors: Ricardo Sobhie
authors: RS
authors: Diaz
mesh_terms: D019380:Anti-HIV Agents / Q000627:therapeutic use*; D024882:Drug Resistance, Viral / Q000235:genetics; D015658:HIV Infections / Q000188:drug therapy* / Q000821:virology; D015497:HIV-1 / Q000187:drug effects* / Q000235:genetics; D006801:Humans; D008826:Microbial Sensitivity Tests; D009154:Mutation / Q000235:genetics; D010641:Phenotype
chemical_list: D019380:Anti-HIV Agents