title: TMPRSS12 Is an Activating Protease for Subtype B Avian Metapneumovirus.
abstract: The entry of avian metapneumovirus (aMPV) into host cells initially requires the fusion of viral and cell membranes, which is exclusively mediated by fusion (F) protein. Proteolysis of aMPV F protein by endogenous proteases of host cells allows F protein to induce membrane fusion; however, these proteases have not been identified. Here, we provide the first evidence that the transmembrane serine protease TMPRSS12 facilitates the cleavage of subtype B aMPV (aMPV/B) F protein. We found that overexpression of TMPRSS12 enhanced aMPV/B F protein cleavage, F protein fusogenicity, and viral replication. Subsequently, knockdown of TMPRSS12 with specific small interfering RNAs (siRNAs) reduced aMPV/B F protein cleavage, F protein fusogenicity, and viral replication. We also found a cleavage motif in the aMPV/B F protein (amino acids 100 and 101) that was recognized by TMPRSS12. The histidine, aspartic acid, and serine residue (HDS) triad of TMPRSS12 was shown to be essential for the proteolysis of aMPV/B F protein via mutation analysis. Notably, we observed TMPRSS12 mRNA expression in target organs of aMPV/B in chickens. Overall, our results indicate that TMPRSS12 is crucial for aMPV/B F protein proteolysis and aMPV/B infectivity and that TMPRSS12 may serve as a target for novel therapeutics and prophylactics for aMPV.
  
  
  OBJECTIVE
  Proteolysis of the aMPV F protein is a prerequisite for F protein-mediated membrane fusion of virus and cell and for aMPV infection; however, the proteases used in vitro and vivo are not clear. A combination of analyses, including overexpression, knockdown, and mutation methods, demonstrated that the transmembrane serine protease TMPRSS12 facilitated cleavage of subtype B aMPV (aMPV/B) F protein. Importantly, we located the motif in the aMPV/B F protein recognized by TMPRSS12 and the catalytic triad in TMPRSS12 that facilitated proteolysis of the aMPV/B F protein. This is the first report on TMPRSS12 as a protease for proteolysis of viral envelope glycoproteins. Our study will shed light on the mechanism of proteolysis of aMPV F protein and pathogenesis of aMPV.
authors.affiliation: Division of Avian Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Nan Gang District, Harbin, Heilongjiang Province, People's Republic of China.
authors.forename: Bingling
authors.initials: B
authors.lastname: Yun
authors.affiliation: Division of Avian Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Nan Gang District, Harbin, Heilongjiang Province, People's Republic of China.
authors.forename: Yao
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Division of Avian Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Nan Gang District, Harbin, Heilongjiang Province, People's Republic of China.
authors.forename: Yongzhen
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Division of Avian Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Nan Gang District, Harbin, Heilongjiang Province, People's Republic of China.
authors.forename: Xiaolu
authors.initials: X
authors.lastname: Guan
authors.affiliation: Division of Avian Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Nan Gang District, Harbin, Heilongjiang Province, People's Republic of China.
authors.forename: Yongqiang
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Division of Avian Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Nan Gang District, Harbin, Heilongjiang Province, People's Republic of China.
authors.forename: Xiaole
authors.initials: X
authors.lastname: Qi
authors.affiliation: Division of Avian Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Nan Gang District, Harbin, Heilongjiang Province, People's Republic of China.
authors.forename: Hongyu
authors.initials: H
authors.lastname: Cui
authors.affiliation: Division of Avian Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Nan Gang District, Harbin, Heilongjiang Province, People's Republic of China.
authors.forename: Changjun
authors.initials: C
authors.lastname: Liu
authors.affiliation: Division of Avian Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Nan Gang District, Harbin, Heilongjiang Province, People's Republic of China.
authors.forename: Yanping
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Division of Avian Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Nan Gang District, Harbin, Heilongjiang Province, People's Republic of China.
authors.forename: Honglei
authors.initials: H
authors.lastname: Gao
authors.affiliation: Division of Avian Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Nan Gang District, Harbin, Heilongjiang Province, People's Republic of China.
authors.forename: Li
authors.initials: L
authors.lastname: Gao
authors.affiliation: Division of Avian Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Nan Gang District, Harbin, Heilongjiang Province, People's Republic of China.
authors.forename: Kai
authors.initials: K
authors.lastname: Li
authors.affiliation: Division of Avian Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Nan Gang District, Harbin, Heilongjiang Province, People's Republic of China ylg@hvri.ac.cn xmw@hvri.ac.cn.
authors.forename: Yulong
authors.initials: Y
authors.lastname: Gao
authors.affiliation: Division of Avian Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Nan Gang District, Harbin, Heilongjiang Province, People's Republic of China ylg@hvri.ac.cn xmw@hvri.ac.cn.|Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Disease and Zoonoses, Yangzhou, People's Republic of China.
authors.forename: Xiaomei
authors.initials: X
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000831:Animals, Newborn; D002460:Cell Line; D002645:Chickens; D002522:Chlorocebus aethiops; D003412:Cricetulus; D004847:Epithelial Cells / Q000201:enzymology / Q000276:immunology / Q000821:virology; D005347:Fibroblasts / Q000201:enzymology / Q000276:immunology / Q000821:virology; D005786:Gene Expression Regulation; D054884:Host-Pathogen Interactions; D029121:Metapneumovirus / Q000235:genetics* / Q000254:growth & development / Q000276:immunology; D008958:Models, Molecular; D018184:Paramyxoviridae Infections / Q000201:enzymology* / Q000276:immunology / Q000821:virology; D011201:Poultry Diseases / Q000201:enzymology* / Q000276:immunology / Q000821:virology; D000072417:Protein Domains; D017433:Protein Structure, Secondary; D059748:Proteolysis; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D014709:Vero Cells; D014760:Viral Fusion Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D053586:Virus Internalization; D014779:Virus Replication
chemical_list: D034741:RNA, Small Interfering; D014760:Viral Fusion Proteins