title: Human immunodeficiency virus type 1 resistance to the small molecule maturation inhibitor 3-O-(3',3'-dimethylsuccinyl)-betulinic acid is conferred by a variety of single amino acid substitutions at the CA-SP1 cleavage site in Gag.
abstract: The compound 3-O-(3',3'-dimethylsuccinyl)-betulinic acid (DSB) potently and specifically inhibits human immunodeficiency virus type 1 (HIV-1) replication by delaying the cleavage of the CA-SP1 junction in Gag, leading to impaired maturation of the viral core. In this study, we investigated HIV-1 resistance to DSB by analyzing HIV-1 mutants encoding a variety of individual amino acid substitutions in the CA-SP1 cleavage site. Three of the substitutions were lethal to HIV-1 replication owing to a deleterious effect on particle assembly. The remaining mutants exhibited a range of replication efficiencies; however, each mutant was capable of replicating in the presence of concentrations of DSB that effectively inhibited wild-type HIV-1. Mutations conferring resistance to DSB also led to impaired binding of the compound to immature HIV-1 virions and loss of DSB-mediated inhibition of cleavage of Gag. Surprisingly, two of the DSB-resistant mutants retained an intermediate ability to bind the compound, suggesting that binding of DSB to immature HIV-1 particles may not be sufficient for antiviral activity. Overall, our results indicate that Gag amino acids L363 and A364 are critical for inhibition of HIV-1 replication by DSB and suggest that these residues form key contacts with the drug in the context of the assembling HIV-1 particle. These results have implications for the design of and screening for novel inhibitors of HIV-1 maturation.
authors.affiliation: Department of Microbiology and Immunology, Vanderbilt University School of Medicine, A-5301 Medical Center North, Nashville, TN 37232-2363, USA.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhou
authors.forename: Chin Ho
authors.initials: CH
authors.lastname: Chen
authors.forename: Christopher
authors.initials: C
authors.lastname: Aiken
mesh_terms: D019943:Amino Acid Substitution / Q000235:genetics*; D019380:Anti-HIV Agents / Q000378:metabolism* / Q000494:pharmacology; D045744:Cell Line, Tumor; D024882:Drug Resistance, Viral / Q000235:genetics*; D015683:Gene Products, gag / Q000235:genetics*; D015497:HIV-1 / Q000187:drug effects / Q000235:genetics*; D006801:Humans; D016296:Mutagenesis; D013386:Succinates / Q000378:metabolism* / Q000494:pharmacology; D014315:Triterpenes / Q000378:metabolism* / Q000494:pharmacology; D019065:Virus Assembly / Q000235:genetics*; D014779:Virus Replication / Q000235:genetics*; D053978:Pentacyclic Triterpenes
chemical_list: D019380:Anti-HIV Agents; D015683:Gene Products, gag; D013386:Succinates; D014315:Triterpenes; C479935:bevirimat; D053978:Pentacyclic Triterpenes