title: Potent inhibition of feline coronaviruses with peptidyl compounds targeting coronavirus 3C-like protease.
abstract: Feline coronavirus infection is common among domestic and exotic felid species and usually associated with mild or asymptomatic enteritis; however, feline infectious peritonitis (FIP) is a fatal disease of cats that is caused by systemic infection with a feline infectious peritonitis virus (FIPV), a variant of feline enteric coronavirus (FECV). Currently, there is no specific treatment approved for FIP despite the importance of FIP as the leading infectious cause of death in young cats. During the replication process, coronavirus produces viral polyproteins that are processed into mature proteins by viral proteases, the main protease (3C-like [3CL] protease) and the papain-like protease. Since the cleavages of viral polyproteins are an essential step for virus replication, blockage of viral protease is an attractive target for therapeutic intervention. Previously, we reported the generation of broad-spectrum peptidyl inhibitors against viruses that possess a 3C or 3CL protease. In this study, we further evaluated the antiviral effects of the peptidyl inhibitors against feline coronaviruses, and investigated the interaction between our protease inhibitor and a cathepsin B inhibitor, an entry blocker, against a feline coronavirus in cell culture. Herein we report that our compounds behave as reversible, competitive inhibitors of 3CL protease, potently inhibited the replication of feline coronaviruses (EC(50) in a nanomolar range) and, furthermore, combination of cathepsin B and 3CL protease inhibitors led to a strong synergistic interaction against feline coronaviruses in a cell culture system.
authors.affiliation: Department of Diagnostic Medicine and Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, 66506, USA. ykim@vet.ksu.edu
authors.forename: Yunjeong
authors.initials: Y
authors.lastname: Kim
authors.forename: Sivakoteswara Rao
authors.initials: SR
authors.lastname: Mandadapu
authors.forename: William C
authors.initials: WC
authors.lastname: Groutas
authors.forename: Kyeong-Ok
authors.initials: KO
authors.lastname: Chang
mesh_terms: D000086042:3C Viral Proteases; D000595:Amino Acid Sequence; D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology*; D002401:Cathepsin B / Q000494:pharmacology; D002415:Cats; D002460:Cell Line; D016765:Coronavirus, Feline / Q000187:drug effects* / Q000502:physiology; D003546:Cysteine Endopeptidases; D004357:Drug Synergism; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010455:Peptides / Q000494:pharmacology*; D011480:Protease Inhibitors / Q000494:pharmacology*; D014764:Viral Proteins / Q000037:antagonists & inhibitors*; D014779:Virus Replication / Q000187:drug effects
chemical_list: D000998:Antiviral Agents; D010455:Peptides; D011480:Protease Inhibitors; D014764:Viral Proteins; D003546:Cysteine Endopeptidases; D002401:Cathepsin B; D000086042:3C Viral Proteases