title: Multidrug-resistant human immunodeficiency virus type 1 strains resulting from combination antiretroviral therapy.
abstract: Multidrug-resistant human immunodeficiency virus type 1 (HIV-1) strains with reverse transcriptase (RT) mutations at codons A62-->V, V75-->I, F77-->L, F116-->Y, and Q151-->M have been reported in patients receiving combination therapy with zidovudine (AZT) and didanosine (ddI). Infectious clones with each mutation alone, all five mutations together, and various combinations of mutations were created by site-directed mutagenesis. Mutation Q151-->M conferred partial resistance to AZT, ddI, zalcitibine, and stavudine, whereas a combination of four mutations conferred increased resistance to AZT, ddI, zalcitibine, and stavudine. The positions of residues 75, 77, and 151 in the three-dimensional crystal structure of HIV-1 RT suggest that these residues may affect the ability of the enzyme to discriminate between deoxynucleoside triphosphates and nucleoside analog RT inhibitors. Replication experiments showed that clones with mutation F77-->L but without V75-->I (HIV-1(77), HIV-1(77,151), and HIV-1(77,116,151) had attenuated growth compared with that of the original HIV-1NL4-3 strain and strains containing mutations at both positions 75 and 77 (HIV-1(75,77,151) and HIV-1(75,77,116,15)). Sequence analysis of viral RNA and proviral DNA from several patients indicated that RT mutations developed in a sequential and cumulative pattern over the course of a 2- to 4-year observation period. The present results suggest that drug resistance and viral replicative capacity both may play a role in selection of HIV-1 RT mutations.
authors.affiliation: Division of Infectious Diseases and Geographic Medicine, Stanford University, California 94305, USA.
authors.forename: A K
authors.initials: AK
authors.lastname: Iversen
authors.forename: R W
authors.initials: RW
authors.lastname: Shafer
authors.forename: K
authors.initials: K
authors.lastname: Wehrly
authors.forename: M A
authors.initials: MA
authors.lastname: Winters
authors.forename: J I
authors.initials: JI
authors.lastname: Mullins
authors.forename: B
authors.initials: B
authors.lastname: Chesebro
authors.forename: T C
authors.initials: TC
authors.lastname: Merigan
mesh_terms: D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology*; D001483:Base Sequence; D002460:Cell Line; D017931:DNA Primers; D004279:DNA, Viral; D016049:Didanosine / Q000494:pharmacology*; D004352:Drug Resistance, Microbial / Q000235:genetics; D018432:Drug Resistance, Multiple / Q000235:genetics; D004359:Drug Therapy, Combination; D015658:HIV Infections / Q000188:drug therapy / Q000821:virology*; D054303:HIV Reverse Transcriptase; D015497:HIV-1 / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D012194:RNA-Directed DNA Polymerase / Q000235:genetics*; D018894:Reverse Transcriptase Inhibitors / Q000494:pharmacology*; D014779:Virus Replication; D015215:Zidovudine / Q000494:pharmacology*
chemical_list: D000998:Antiviral Agents; D017931:DNA Primers; D004279:DNA, Viral; D018894:Reverse Transcriptase Inhibitors; D015215:Zidovudine; D054303:HIV Reverse Transcriptase; D012194:RNA-Directed DNA Polymerase; D016049:Didanosine