title: A novel point mutation at position 156 of reverse transcriptase from feline immunodeficiency virus confers resistance to the combination of (-)-beta-2',3'-dideoxy-3'-thiacytidine and 3'-azido-3'-deoxythymidine.
abstract: Mutants of feline immunodeficiency virus (FIV) resistant to (-)-beta-2',3'-dideoxy-3'-thiacytidine (3TC) were selected by culturing virus in the presence of increasing stepwise concentrations of 3TC. Two plaque-purified variants were isolated from the original mutant population, and both of these mutants were resistant to 3TC. Surprisingly, these mutants were also phenotypically resistant to 3'-azido-3'-deoxythymidine (AZT) and to the combination of 3TC and AZT. Purified reverse transcriptase (RT) from one of these plaque-purified mutants was resistant to the 5'-triphosphates of 3TC and AZT. DNA sequence analysis of the RT-encoding region of the pol gene amplified from the plaque-purified mutants revealed a Pro-to-Ser mutation at position 156 of RT. A site-directed mutant of FIV engineered to contain this Pro-156-Ser mutation was resistant to 3TC, AZT, and the combination of 3TC and AZT, confirming the role of the Pro-156-Ser mutation in the resistance of FIV to these two nucleoside analogs. This represents the first report of a lentiviral mutant resistant to the combination of AZT and 3TC due to a single, unique point mutation.
authors.affiliation: Division of Biological Sciences, the University of Montana, Missoula 59812, USA.
authors.forename: R A
authors.initials: RA
authors.lastname: Smith
authors.forename: K M
authors.initials: KM
authors.lastname: Remington
authors.forename: B D
authors.initials: BD
authors.lastname: Preston
authors.forename: R F
authors.initials: RF
authors.lastname: Schinazi
authors.forename: T W
authors.initials: TW
authors.lastname: North
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002415:Cats; D002460:Cell Line; D004347:Drug Interactions; D004352:Drug Resistance, Microbial / Q000235:genetics; D016089:Immunodeficiency Virus, Feline / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D019259:Lamivudine / Q000494:pharmacology*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D017354:Point Mutation; D011392:Proline / Q000235:genetics* / Q000378:metabolism; D012194:RNA-Directed DNA Polymerase / Q000235:genetics* / Q000378:metabolism; D018894:Reverse Transcriptase Inhibitors / Q000494:pharmacology*; D017422:Sequence Analysis, DNA; D012694:Serine / Q000235:genetics* / Q000378:metabolism; D010948:Viral Plaque Assay; D015215:Zidovudine / Q000494:pharmacology*
chemical_list: D018894:Reverse Transcriptase Inhibitors; D019259:Lamivudine; D012694:Serine; D015215:Zidovudine; D011392:Proline; D012194:RNA-Directed DNA Polymerase