title: Nonnucleoside reverse transcriptase inhibitor phenotypic hypersusceptibility can be demonstrated in different assays.
abstract: BACKGROUND
  HIV-1 isolates harboring multiple nucleoside reverse transcriptase inhibitor (NRTI) resistance mutations are more susceptible ("hypersusceptible") to the nonnucleoside reverse transcriptase inhibitors (NNRTIs) than isolates lacking NRTI resistance mutations, but this has only been reported with a single-cycle replication phenotypic assay. In fact, there was a report that a commercial multicycle assay did not readily detect hypersusceptibility.
  
  
  OBJECTIVE
  To see whether NNRTI hypersusceptibility can be demonstrated in other types of phenotypic assays, including multicycle assays and enzyme inhibition assays.
  
  
  METHODS
  The susceptibility of HIV-1 clones derived from different patients in multicycle assays was tested in peripheral blood mononuclear cells (PBMCs) and in an established cell line. In addition, the reverse transcriptase (RT) of many of these clones was expressed and their susceptibility tested in an RT inhibition assay. Nevirapine and efavirenz susceptibilities were tested and compared with a control wild-type virus or RT.
  
  
  RESULTS
  Hypersusceptibility to nevirapine and efavirenz was detected using each of the methods described above. R values correlating the other methods with single-cycle assay values were between 0.66 and 0.96. In addition to the high correlations, the different methods gave similar numeric results.
  
  
  CONCLUSIONS
  NNRTI hypersusceptibility is readily seen in multicycle susceptibility assays and in enzyme inhibition assays.
authors.affiliation: Center for AIDS Research, Division of Infectious Diseases, Stanford University, Stanford, CA 97305, USA. nshulman@stanford.edu
authors.forename: Nancy S
authors.initials: NS
authors.lastname: Shulman
authors.forename: Jamael
authors.initials: J
authors.lastname: Delgado
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Bosch
authors.forename: Mark A
authors.initials: MA
authors.lastname: Winters
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Johnston
authors.forename: Robert W
authors.initials: RW
authors.lastname: Shafer
authors.forename: David A
authors.initials: DA
authors.lastname: Katzenstein
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Merigan
mesh_terms: D019943:Amino Acid Substitution; D003062:Codon / Q000235:genetics; D004342:Drug Hypersensitivity; D005838:Genotype; D054303:HIV Reverse Transcriptase / Q000235:genetics*; D015497:HIV-1 / Q000187:drug effects*; D006801:Humans; D010641:Phenotype; D012367:RNA, Viral / Q000097:blood / Q000302:isolation & purification; D018894:Reverse Transcriptase Inhibitors / Q000009:adverse effects*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019562:Viral Load
chemical_list: D003062:Codon; D012367:RNA, Viral; D018894:Reverse Transcriptase Inhibitors; D054303:HIV Reverse Transcriptase