title: Competitive capacity of HIV-1 strains carrying M184I or Y181I drug-resistant mutations.
abstract: BACKGROUND
  Virus with nucleoside reverse transcriptase inhibitors (NRTIs) or nonnucleoside reverse transcriptase inhibitors (NNRTIs) resistant mutations show different evolution tendencies when the anti-viral therapies are interrupted. Understanding the replication fitness of drug-resistant virus is important for the study of the prevalence of drug-resistance. For this purpose, we characterized the replication capacity of HIV-1 virus carrying lamivudine (3TC) or nevirapine (NVP) resistant mutations.
  
  
  METHODS
  3TC and NVP resistant variants were induced in vitro by selecting wild type virus in the presence of drugs. For the competitive replication assay, drug-resistant variants were cocultured with wild-type virus in the presence or absence of drugs. The ratios of the viral species were determined over time by using a real-time RT-PCR-based assay.
  
  
  RESULTS
  3TC-resistant (M184I mutation) and NVP-resistant (Y181I mutation) virus should be selected in vitro in two different ways. The competitive replication assay showed that the ratio of virus carrying a M184I mutation increased from 98.8%, while the wild type virus decreased to 1.2% after 4 passages in the presence of 3TC; the percentage of virus carrying the Y181I mutation increased to 90.5%, while wild type virus decreased to 9.5% in the presence of NVP. In the absence of drugs, the ratio of virus carrying the M184I mutation decreased to 5.3%, while wild type virus increased to 94.7%; the ratio of virus carrying Y181I increased to 75%, while wild type virus decreased to 25% after 4 passages.
  
  
  CONCLUSIONS
  The NVP-resistant virus is fitter than wild type virus even in the absence of NVP that may be the reason that NNRTIs-resistant virus is spreading quickly.
authors.affiliation: Department of AIDS Research, State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China.
authors.forename: Jue
authors.initials: J
authors.lastname: Li
authors.forename: Lin
authors.initials: L
authors.lastname: Li
authors.forename: Han-ping
authors.initials: HP
authors.lastname: Li
authors.forename: Dao-min
authors.initials: DM
authors.lastname: Zhuang
authors.forename: Si-yang
authors.initials: SY
authors.lastname: Liu
authors.forename: Yong-jian
authors.initials: YJ
authors.lastname: Liu
authors.forename: Zuo-yi
authors.initials: ZY
authors.lastname: Bao
authors.forename: Zheng
authors.initials: Z
authors.lastname: Wang
authors.forename: Jing-yun
authors.initials: JY
authors.lastname: Li
mesh_terms: D002460:Cell Line; D024882:Drug Resistance, Viral / Q000235:genetics*; D015497:HIV-1 / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D006801:Humans; D019259:Lamivudine / Q000494:pharmacology; D009154:Mutation; D019829:Nevirapine / Q000494:pharmacology; D018894:Reverse Transcriptase Inhibitors / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014779:Virus Replication / Q000235:genetics / Q000502:physiology
chemical_list: D018894:Reverse Transcriptase Inhibitors; D019259:Lamivudine; D019829:Nevirapine