title: Sensitivity of NS3 serine proteases from hepatitis C virus genotypes 2 and 3 to the inhibitor BILN 2061.
abstract: Hepatitis C virus (HCV) displays a high degree of genetic variability. Six genotypes and more than 50 subtypes have been identified to date. In this report, kinetic profiles were determined for NS3 proteases of genotypes 1a, 1b, 2ac, 2b, and 3a, revealing no major differences in activity. In vitro sensitivity studies with BILN 2061 showed a decrease in affinity for proteases of genotypes 2 and 3 (K(i), 80 to 90 nM) compared to genotype 1 enzymes (K(i), 1.5 nM). To understand the reduced sensitivity of genotypes 2 and 3 to BILN 2061, active-site residues in the proximity of the inhibitor binding site were replaced in the genotype-1b enzyme with the corresponding genotype-2b or -3a residues. The replacement of five residues at positions 78, 79, 80, 122, and 132 accounted for most of the reduced sensitivity of genotype 2b, while replacement of residue 168 alone could account for the reduced sensitivity of genotype 3a. BILN 2061 remains a potent inhibitor of these non-genotype-1 NS3-NS4A proteins, with K(i) values below 100 nM. This in vitro potency, in conjunction with the good pharmacokinetic data reported for humans, suggests that there is potential for BILN 2061 as an antiviral agent for individuals infected with non-genotype-1 HCV.
authors.affiliation: Department of Biological Sciences, Boehringer Ingelheim (Canada) Ltd, Research and Development, Laval, Québec H7S 2G5, Canada. dthibeault@lav.boehringer-ingelheim.com
authors.forename: Diane
authors.initials: D
authors.lastname: Thibeault
authors.forename: Christiane
authors.initials: C
authors.lastname: Bousquet
authors.forename: Rock
authors.initials: R
authors.lastname: Gingras
authors.forename: Lisette
authors.initials: L
authors.lastname: Lagacé
authors.forename: Roger
authors.initials: R
authors.lastname: Maurice
authors.forename: Peter W
authors.initials: PW
authors.lastname: White
authors.forename: Daniel
authors.initials: D
authors.lastname: Lamarre
mesh_terms: D000595:Amino Acid Sequence; D000998:Antiviral Agents / Q000494:pharmacology*; D001665:Binding Sites; D002219:Carbamates / Q000494:pharmacology*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D005838:Genotype; D016174:Hepacivirus / Q000145:classification / Q000187:drug effects* / Q000201:enzymology*; D006801:Humans; D007700:Kinetics; D047028:Macrocyclic Compounds; D008826:Microbial Sensitivity Tests / Q000379:methods; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D011804:Quinolines; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology*; D013844:Thiazoles / Q000494:pharmacology*; D017361:Viral Nonstructural Proteins / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000235:genetics; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases
chemical_list: D000998:Antiviral Agents; D002219:Carbamates; D047028:Macrocyclic Compounds; D011804:Quinolines; D015842:Serine Proteinase Inhibitors; D013844:Thiazoles; D017361:Viral Nonstructural Proteins; C479555:BILN 2061; C084422:NS3 protein, hepatitis C virus; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases