title: Spontaneous mutations in the human immunodeficiency virus type 1 gag gene that affect viral replication in the presence of cyclosporins.
abstract: Human immunodeficiency virus type 1 mutants that are resistant to inhibition by cyclosporins arise spontaneously in vitro during propagation in a HeLa-CD4+ cell line in the presence of a nonimmunosuppressive analog of cyclosporin A. Interestingly, the phenotype of all of the mutants examined is drug resistant and drug dependent, with both cyclosporin A and its analog. Four independently isolated mutants have been analyzed genetically by construction of recombinant proviruses in the NL4-3 parental strain background and subsequent testing of the chimeric viruses in HeLa cells. The cyclosporin-resistant, cyclosporin-dependent phenotype consistently transfers with a 1.3-kb fragment of gag, within which the four mutants share one of two possible single amino acid exchanges in a proline-rich stretch in the capsid domain of Pr55gag. These mutants provide the first evidence that mutations in human immunodeficiency virus type 1 gag confer resistance to cyclosporins; however, replication is conditional on the presence of the drug. In the T-cell line CEM, replication of the recombinant mutant viruses is also cyclosporin dependent. The drug-dependent replication in HeLa cells is stringent, and in the absence of cyclosporin only revertant viruses with the parental phenotype grow out of cultures infected with cyclosporin-dependent virus. In at least one isolate examined, the revertant phenotype appears to be due to suppressor mutations near the proline-rich region.
authors.affiliation: Sandoz Forschungsinstitut, Vienna, Austria.
authors.forename: C
authors.initials: C
authors.lastname: Aberham
authors.forename: S
authors.initials: S
authors.lastname: Weber
authors.forename: W
authors.initials: W
authors.lastname: Phares
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D016572:Cyclosporine / Q000494:pharmacology*; D004351:Drug Resistance; D015750:Genes, gag; D015497:HIV-1 / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D014779:Virus Replication / Q000187:drug effects*
chemical_list: D016572:Cyclosporine