title: In vitro HIV-1 evolution in response to triple reverse transcriptase inhibitors & in silico phenotypic analysis.
abstract: BACKGROUND
  Effectiveness of ART regimens strongly depends upon complex interactions between the selective pressure of drugs and the evolution of mutations that allow or restrict drug resistance.
  
  
  METHODS
  Four clinical isolates from NRTI-exposed, NNRTI-naive subjects were passaged in increasing concentrations of NVP in combination with 1 µM 3 TC and 2 µM ADV to assess selective pressures of multi-drug treatment. A novel parameter inference procedure, based on a stochastic viral growth model, was used to estimate phenotypic resistance and fitness from in vitro combination passage experiments.
  
  
  RESULTS
  Newly developed mathematical methods estimated key phenotypic parameters of mutations arising through selective pressure exerted by 3 TC and NVP. Concentrations of 1 µM 3 TC maintained the M184V mutation, which was associated with intrinsic fitness deficits. Increasing NVP concentrations selected major NNRTI resistance mutations. The evolutionary pathway of NVP resistance was highly dependent on the viral genetic background, epistasis as well as stochasticity. Parameter estimation indicated that the previously unrecognized mutation L228Q was associated with NVP resistance in some isolates.
  
  
  CONCLUSIONS
  Serial passage of viruses in the presence of multiple drugs may resemble the selection of mutations observed among treated individuals and populations in vivo and indicate evolutionary preferences and restrictions. Phenotypic resistance estimated here "in silico" from in vitro passage experiments agreed well with previous knowledge, suggesting that the unique combination of "wet-" and "dry-lab" experimentation may improve our understanding of HIV-1 resistance evolution in the future.
authors.affiliation: Department of Pediatrics, Division of Pneumonology-Immunology, Charité University Medical Center, Berlin, Germany.
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Rath
authors.forename: Kaveh Pouran
authors.initials: KP
authors.lastname: Yousef
authors.forename: David K
authors.initials: DK
authors.lastname: Katzenstein
authors.forename: Robert W
authors.initials: RW
authors.lastname: Shafer
authors.forename: Christof
authors.initials: C
authors.lastname: Schütte
authors.forename: Max
authors.initials: M
authors.lastname: von Kleist
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Merigan
mesh_terms: D019943:Amino Acid Substitution / Q000235:genetics; D003198:Computer Simulation; D004305:Dose-Response Relationship, Drug; D024882:Drug Resistance, Viral / Q000187:drug effects; D056084:Genetic Fitness; D015497:HIV-1 / Q000187:drug effects* / Q000254:growth & development / Q000302:isolation & purification; D006801:Humans; D007700:Kinetics; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D018894:Reverse Transcriptase Inhibitors / Q000494:pharmacology*; D012692:Serial Passage; D013269:Stochastic Processes; D013997:Time Factors
chemical_list: D018894:Reverse Transcriptase Inhibitors