title: The base component of 3'-azido-2',3'-dideoxynucleosides influences resistance mutations selected in HIV-1 reverse transcriptase.
abstract: We recently reported that HIV-1 resistant to 3'-azido-3'-deoxythymidine (AZT) is not cross-resistant to 3'-azido-2',3'-dideoxypurines. This finding suggested that the nucleoside base is a major determinant of HIV-1 resistance to nucleoside analogs. To further explore this hypothesis, we conducted in vitro selection experiments by serial passage of HIV-1(LAI) in MT-2 cells in increasing concentrations of 3'-azido-2',3'-dideoxyguanosine (3'-azido-ddG), 3'-azido-2',3'-dideoxycytidine (3'-azido-ddC), or 3'-azido-2',3'-dideoxyadenosine (3'-azido-ddA). 3'-Azido-ddG selected for virus that was 5.3-fold resistant to 3'-azido-ddG compared to wild-type HIV-1(LAI) passaged in the absence of drug. Population sequencing of the entire reverse transcriptase (RT) gene identified L74V, F77L, and L214F mutations in the polymerase domain and K476N and V518I mutations in the RNase H domain. However, when introduced into HIV-1 by site-directed mutagenesis, these 5 mutations only conferred ∼2.0-fold resistance. Single-genome sequencing analyses of the selected virus revealed a complex population of mutants that all contained L74V and L214F linked to other mutations, including ones not identified during population sequencing. Recombinant HIV-1 clones containing RT derived from single sequences exhibited 3.2- to 4.0-fold 3'-azido-ddG resistance. In contrast to 3'-azido-ddG, 3'-azido-ddC selected for the V75I mutation in HIV-1 RT that conferred 5.9-fold resistance, compared to the wild-type virus. Interestingly, we were unable to select HIV-1 that was resistant to 3'-azido-ddA, even at concentrations of 3'-azido-ddA that yielded high intracellular levels of 3'-azido-ddA-5'-triphosphate. Taken together, these findings show that the nucleoside base is a major determinant of HIV-1 resistance mechanisms that can be exploited in the design of novel nucleoside RT inhibitors.
authors.affiliation: University of Pittsburgh School of Medicine, Department of Medicine, Division of Infectious Diseases, Pittsburgh, PA 15261, USA.
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Meteer
authors.forename: Dianna
authors.initials: D
authors.lastname: Koontz
authors.forename: Ghazia
authors.initials: G
authors.lastname: Asif
authors.forename: Hong-wang
authors.initials: HW
authors.lastname: Zhang
authors.forename: Mervi
authors.initials: M
authors.lastname: Detorio
authors.forename: Sarah
authors.initials: S
authors.lastname: Solomon
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Coats
authors.forename: Nicolas
authors.initials: N
authors.lastname: Sluis-Cremer
authors.forename: Raymond F
authors.initials: RF
authors.lastname: Schinazi
authors.forename: John W
authors.initials: JW
authors.lastname: Mellors
mesh_terms: D019380:Anti-HIV Agents / Q000494:pharmacology*; D001386:Azides / Q000494:pharmacology; D001483:Base Sequence; D016048:Dideoxyadenosine / Q000031:analogs & derivatives / Q000494:pharmacology; D015224:Dideoxynucleosides / Q000494:pharmacology*; D024882:Drug Resistance, Viral; D054303:HIV Reverse Transcriptase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D015497:HIV-1 / Q000187:drug effects* / Q000235:genetics; D016297:Mutagenesis, Site-Directed; D018894:Reverse Transcriptase Inhibitors / Q000494:pharmacology*; D017423:Sequence Analysis, RNA; D016047:Zalcitabine / Q000031:analogs & derivatives / Q000494:pharmacology; D015215:Zidovudine / Q000494:pharmacology
chemical_list: C569661:3'-azido-2',3'-dideoxyadenosine; C569662:3'-azido-2',3'-dideoxycytidine; D019380:Anti-HIV Agents; D001386:Azides; D015224:Dideoxynucleosides; D018894:Reverse Transcriptase Inhibitors; D015215:Zidovudine; D016048:Dideoxyadenosine; C051073:3'-azido-2',3'-dideoxyguanosine; D016047:Zalcitabine; D054303:HIV Reverse Transcriptase