title: Viral evolution in response to the broad-based retroviral protease inhibitor TL-3.
abstract: TL-3 is a protease inhibitor developed using the feline immunodeficiency virus protease as a model. It has been shown to efficiently inhibit replication of human, simian, and feline immunodeficiency viruses and therefore has broad-based activity. We now demonstrate that TL-3 efficiently inhibits the replication of 6 of 12 isolates with confirmed resistance mutations to known protease inhibitors. To dissect the spectrum of molecular changes in protease and viral properties associated with resistance to TL-3, a panel of chronological in vitro escape variants was generated. We have virologically and biochemically characterized mutants with one (V82A), three (M46I/F53L/V82A), or six (L24I/M46I/F53L/L63P/V77I/V82A) changes in the protease and structurally modeled the protease mutant containing six changes. Virus containing six changes was found to be 17-fold more resistant to TL-3 in cell culture than was wild-type virus but maintained similar in vitro replication kinetics compared to the wild-type virus. Analyses of enzyme activity of protease variants with one, three, and six changes indicated that these enzymes, compared to wild-type protease, retained 40, 47, and 61% activity, respectively. These results suggest that deficient protease enzymatic activity is sufficient for function, and the observed protease restoration might imply a selective advantage, at least in vitro, for increased protease activity.
authors.affiliation: Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California 92037, USA.
authors.forename: B
authors.initials: B
authors.lastname: Bühler
authors.forename: Y C
authors.initials: YC
authors.lastname: Lin
authors.forename: G
authors.initials: G
authors.lastname: Morris
authors.forename: A J
authors.initials: AJ
authors.lastname: Olson
authors.forename: C H
authors.initials: CH
authors.lastname: Wong
authors.forename: D D
authors.initials: DD
authors.lastname: Richman
authors.forename: J H
authors.initials: JH
authors.lastname: Elder
authors.forename: B E
authors.initials: BE
authors.lastname: Torbett
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002415:Cats; D019143:Evolution, Molecular; D016679:Genome, Viral; D006801:Humans; D008969:Molecular Sequence Data; D011480:Protease Inhibitors / Q000494:pharmacology*; D012190:Retroviridae / Q000187:drug effects* / Q000235:genetics*
chemical_list: D011480:Protease Inhibitors