title: The N-terminal domain of Npro of classical swine fever virus determines its stability and regulates type I IFN production.
abstract: The viral protein Npro is unique to the genus Pestivirus within the family Flaviviridae. After autocatalytic cleavage from the nascent polyprotein, Npro suppresses type I IFN (IFN-α/β) induction by mediating proteasomal degradation of IFN regulatory factor 3 (IRF-3). Previous studies found that the Npro-mediated IRF-3 degradation was dependent of a TRASH domain in the C-terminal half of Npro coordinating zinc by means of the amino acid residues C112, C134, D136 and C138. Interestingly, four classical swine fever virus (CSFV) isolates obtained from diseased pigs in Thailand in 1993 and 1998 did not suppress IFN-α/β induction despite the presence of an intact TRASH domain. Through systematic analyses, it was found that an amino acid mutation at position 40 or mutations at positions 17 and 61 in the N-terminal half of Npro of these four isolates were related to the lack of IRF-3-degrading activity. Restoring a histidine at position 40 or both a proline at position 17 and a lysine at position 61 based on the sequence of a functional Npro contributed to higher stability of the reconstructed Npro compared with the Npro from the Thai isolate. This led to enhanced interaction of Npro with IRF-3 along with its degradation by the proteasome. The results of the present study revealed that amino acid residues in the N-terminal domain of Npro are involved in the stability of Npro, in interaction of Npro with IRF-3 and subsequent degradation of IRF-3, leading to downregulation of IFN-α/β production.
authors: 1Laboratory of Microbiology, Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo 060-0818, Japan.
authors: Junki
authors: J
authors: Mine
authors: 1Laboratory of Microbiology, Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo 060-0818, Japan.
authors: Tomokazu
authors: T
authors: Tamura
authors: 1Laboratory of Microbiology, Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo 060-0818, Japan.
authors: Kazuya
authors: K
authors: Mitsuhashi
authors: 1Laboratory of Microbiology, Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo 060-0818, Japan.
authors: Masatoshi
authors: M
authors: Okamatsu
authors: 2National Institute of Animal Health, Kaset Klang, Chatuchak, Bangkok 10900, Thailand.
authors: Sujira
authors: S
authors: Parchariyanon
authors: 2National Institute of Animal Health, Kaset Klang, Chatuchak, Bangkok 10900, Thailand.
authors: Wasana
authors: W
authors: Pinyochon
authors: 3The Institute of Virology and Immunology IVI, Sensemattstrasse 293, 3147 Mittelhäusern, Switzerland.
authors: Nicolas
authors: N
authors: Ruggli
authors: 3The Institute of Virology and Immunology IVI, Sensemattstrasse 293, 3147 Mittelhäusern, Switzerland.
authors: Jon-Duri
authors: JD
authors: Tratschin
authors: 1Laboratory of Microbiology, Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo 060-0818, Japan 4Research Center for Zoonosis Control, Hokkaido University, Sapporo 001-0020, Japan 5Global Station for Zoonosis Control, Global Institution for Collaborative Research and Education (GI-CoRE), Hokkaido University, Sapporo 001-0020, Japan.
authors: Hiroshi
authors: H
authors: Kida
authors: 5Global Station for Zoonosis Control, Global Institution for Collaborative Research and Education (GI-CoRE), Hokkaido University, Sapporo 001-0020, Japan 1Laboratory of Microbiology, Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo 060-0818, Japan.
authors: Yoshihiro
authors: Y
authors: Sakoda
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D006691:Classical Swine Fever / Q000821:virology; D006692:Classical Swine Fever Virus / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D004252:DNA Mutational Analysis; D015536:Down-Regulation; D010450:Endopeptidases / Q000737:chemistry* / Q000235:genetics / Q000276:immunology*; D054884:Host-Pathogen Interactions; D050835:Interferon Regulatory Factors / Q000037:antagonists & inhibitors*; D007370:Interferon Type I / Q000037:antagonists & inhibitors*; D050505:Mutant Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D020125:Mutation, Missense; D011485:Protein Binding; D025941:Protein Interaction Mapping; D055550:Protein Stability; D017434:Protein Structure, Tertiary; D013552:Swine; D013785:Thailand; D014764:Viral Proteins / Q000737:chemistry* / Q000235:genetics / Q000276:immunology*
chemical_list: D050835:Interferon Regulatory Factors; D007370:Interferon Type I; D050505:Mutant Proteins; D014764:Viral Proteins; D010450:Endopeptidases; C505229:N(pro) protein, swine fever virus