title: Reverse transcriptase mutations 118I, 208Y, and 215Y cause HIV-1 hypersusceptibility to non-nucleoside reverse transcriptase inhibitors.
abstract: BACKGROUND
  HIV-1 hypersusceptibility to non-nucleoside reverse transcriptase inhibitors (NNRTI) improves the response to NNRTI-containing regimens. The genetic basis for NNRTI hypersusceptibility was partly defined in our earlier analyses of a paired genotype-phenotype dataset of viral isolates from treatment-experienced patients, in which we identified reverse transcriptase mutations V118I, H208Y, and T215Y as being strongly associated with NNRTI hypersusceptibility.
  
  
  OBJECTIVE
  We evaluated the role of these mutations in NNRTI hypersusceptibility by site-directed mutagenesis and phenotypic analysis of HIV-1 recombinants.
  
  
  METHODS
  Drug susceptibility and replication capacity were determined in single cycle assays. Hypersusceptibility was defined by a statistically significant (P < 0.01; Student's t-test) mean fold-change in 50% inhibitory concentration (IC50) of less than 0.4.
  
  
  RESULTS
  The single mutations V118I, H208Y, and T215Y did not show hypersusceptibility to efavirenz with mean fold-change of 0.58, 0.55, and 0.70, respectively (P < 0.01 and P = 0.12). The H208Y/T215Y and V118I/H208Y/T215Y mutants showed marked hypersusceptibility to efavirenz, having mean fold-change values of 0.27 and 0.20, respectively (P < 0.001). In addition, H208Y/T215Y, V118I/T215Y, and V118I/H208Y/T215Y were hypersusceptible to delavirdine and nevirapine. The V118I/T215Y mutant was not replication impaired; whereas H208Y/T215Y and V118I/H208Y/T215Y had significantly (P < 0.01) reduced replication capacities of 40 and 35% of wild-type, respectively.
  
  
  CONCLUSIONS
  Different combinations of V118I, H208Y, and T215Y produce NNRTI hypersusceptibility. The V118I/T215Y mutant is hypersusceptible to delavirdine and nevirapine without reduced replication capacity, whereas the H208Y/T215Y and V118I/H208Y/T215Y mutants are hypersusceptible to all NNRTI and show impaired replication. These findings suggest that more than one mechanism is involved in NNRTI hypersusceptibility.
authors.affiliation: School of Medicine, University of Pittsburgh, 3550 Terrace Street, Pittsburgh, PA 15261, USA.
authors.forename: Shauna A
authors.initials: SA
authors.lastname: Clark
authors.forename: Nancy S
authors.initials: NS
authors.lastname: Shulman
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Bosch
authors.forename: John W
authors.initials: JW
authors.lastname: Mellors
mesh_terms: D000480:Alkynes; D048588:Benzoxazines; D003062:Codon / Q000235:genetics; D003521:Cyclopropanes; D020008:Delavirdine / Q000494:pharmacology; D024882:Drug Resistance, Viral / Q000235:genetics; D015497:HIV-1 / Q000187:drug effects / Q000235:genetics*; D009154:Mutation / Q000235:genetics; D019829:Nevirapine / Q000494:pharmacology; D010078:Oxazines / Q000494:pharmacology; D010641:Phenotype; D011995:Recombination, Genetic / Q000235:genetics; D018894:Reverse Transcriptase Inhibitors / Q000494:pharmacology*; D014779:Virus Replication / Q000187:drug effects
chemical_list: D000480:Alkynes; D048588:Benzoxazines; D003062:Codon; D003521:Cyclopropanes; D010078:Oxazines; D018894:Reverse Transcriptase Inhibitors; D019829:Nevirapine; D020008:Delavirdine; C098320:efavirenz