Skip Navigation LinksHome > March 1, 2011 - Volume 56 - Issue 3 > Mapping and Characterization of Vicriviroc Resistance Mutati...
JAIDS Journal of Acquired Immune Deficiency Syndromes:
doi: 10.1097/QAI.0b013e3181ff63ee
Basic and Translational Science

Mapping and Characterization of Vicriviroc Resistance Mutations From HIV-1 Isolated from Treatment-Experienced Subjects Enrolled in a Phase II Study (VICTOR-E1)

McNicholas, Paul M PhD*; Mann, Paul A MPH*; BSc, Lisa Wojcik*; PhD, Ping Qiu†; Lee, Erin RN‡; McCarthy, Michael MD‡; Shen, Junwu PhD§; Black, Todd A PhD*; Strizki, Julie M PhD*

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Objectives: In the phase 2 VICTOR-E1 study, treatment-experienced subjects receiving 20 mg or 30 mg of the CCR5 antagonist vicriviroc (VCV), with a boosted protease containing optimized background regimen, experienced significantly greater reductions in HIV-1 viral load compared with control subjects. Among the 79 VCV-treated subjects, 15 experienced virologic failure, and of these 5 had VCV-resistant virus. This study investigated the molecular basis for the changes in susceptibility to VCV in these subjects.

Methods: Sequence analysis and phenotypic susceptibility testing was performed on envelope clones from VCV-resistant virus. For select clones, an exchange of mutations in the V3 loop was performed between phenotypically resistant clones and the corresponding susceptible clones.

Results: Phenotypic resistance was manifest by reductions in the maximum percent inhibition. Clonal analysis of envelopes from the 5 subjects identified multiple amino acid changes in gp160 that were exclusive to the resistant clones, however, none of the changes were conserved between subjects. Introduction of V3 loop substitutions from the resistant clones into the matched susceptible clones was not sufficient to reproduce the resistant phenotype. Likewise, changing the substitutions in the V3 loops from resistant clones to match susceptible clones only restored susceptibility in 1 clone.

Conclusions: There were no clearly conserved patterns of mutations in gp160 associated with phenotypic resistance to VCV and mutations both within and outside of the V3 loop contributed to the resistance phenotype. These data suggest that genotypic tests for VCV susceptibility may require larger training sets and additional information beyond V3 sequences.

© 2011 Lippincott Williams & Wilkins, Inc.


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