3C protein of feline coronavirus inhibits viral replication independently of the autophagy pathway.
Feline coronavirus (FCoV) can cause either asymptomatic enteric infection or fatal peritonitis in cats. Although the mutation of FCoV accessory gene 3c has been suggested to be related to the occurrence of feline infectious peritonitis (FIP), how the 3C protein is involved in this phenomenon remains unknown. To investigate the role of the 3C protein, a full-length 3c gene was transiently expressed and the cytoplasmic distribution of the protein was found to be primarily in the perinuclear region. Using 3c-stable expression cells, the replication of a 3c-defective FCoV strain was titrated and a significant decrease in replication (p<0.05) was observed. The mechanism underlying the decreased FIPV replication caused by the 3C protein was further investigated; neither the induction nor inhibition of autophagy rescued the viral replication. Taken together, our data suggest that the 3C protein might have a virulence-suppressing effect in FCoV-infected cats. Deletion of the 3c gene could therefore cause more efficient viral replication, which leads to a fatal infection.
Graduate Institute of Veterinary Medicine, Department of Veterinary Medicine, School of Veterinary Medicine, National Taiwan University, Taipei 10617, Taiwan.
Li-En
LE
Hsieh
Wei-Pang
WP
Huang
Da-Jay
DJ
Tang
Ying-Ting
YT
Wang
Ching-Tang
CT
Chen
Ling-Ling
LL
Chueh
D000818:Animals; D001343:Autophagy / Q000502:physiology; D002415:Cats; D002478:Cells, Cultured; D000086782:Coronavirus 3C Proteases; D016765:Coronavirus, Feline / Q000472:pathogenicity / Q000502:physiology*; D003546:Cysteine Endopeptidases / Q000096:biosynthesis / Q000502:physiology*; D016766:Feline Infectious Peritonitis / Q000821:virology*; D005260:Female; D008297:Male; D014774:Virulence / Q000502:physiology; D014779:Virus Replication / Q000502:physiology*
D003546:Cysteine Endopeptidases; D000086782:Coronavirus 3C Proteases
3C protein; 3c gene; Autophagy; Feline coronavirus; Function