Nonnucleoside reverse transcriptase inhibitor phenotypic hypersusceptibility can be demonstrated in different assays.
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.
Shulman
Nancy S
NS
Center for AIDS Research, Division of Infectious Diseases, Stanford University, Stanford, CA 97305, USA. nshulman@stanford.edu
Delgado
Jamael
J
Bosch
Ronald J
RJ
Winters
Mark A
MA
Johnston
Elizabeth
E
Shafer
Robert W
RW
Katzenstein
David A
DA
Merigan
Thomas C
TC
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
D003062:Codon; D012367:RNA, Viral; D018894:Reverse Transcriptase Inhibitors; D054303:HIV Reverse Transcriptase