title: Receptor-bound porcine epidemic diarrhea virus spike protein cleaved by trypsin induces membrane fusion.
abstract: Porcine epidemic diarrhea virus (PEDV) infection in Vero cells is facilitated by trypsin through an undefined mechanism. The present study describes the mode of action of trypsin in enhancing PEDV infection in Vero cells during different stage of the virus life cycle. During the viral entry stage, trypsin increased the penetration of Vero-cell-attached PEDV by approximately twofold. However, trypsin treatment of viruses before receptor binding did not enhance infectivity, indicating that receptor binding is essentially required for trypsin-mediated entry upon PEDV infection. Trypsin treatment during the budding stage of virus infection induces an obvious cytopathic effect in infected cells. Furthermore, we also show that the PEDV spike (S) glycoprotein is cleaved by trypsin in virions that are bound to the receptor, but not in free virions. These findings indicate that trypsin affects only cell-attached PEDV and increases infectivity and syncytium formation in PEDV-infected Vero cells by cleavage of the PEDV S protein. These findings strongly suggest that the PEDV S protein may undergo a conformational change after receptor binding and cleavage by exogenous trypsin, which induces membrane fusion.
authors.affiliation: Laboratory of Infectious Diseases, Animal Hospital, College of Veterinary Medicine, Chungnam National University, 220 Gungdong, Yuseong, Daejeon 305-764, Korea.
authors.forename: Jung-Eun
authors.initials: JE
authors.lastname: Park
authors.forename: Deu John M
authors.initials: DJ
authors.lastname: Cruz
authors.forename: Hyun-Jin
authors.initials: HJ
authors.lastname: Shin
mesh_terms: D000818:Animals; D002522:Chlorocebus aethiops; D018352:Coronavirus Infections / Q000378:metabolism* / Q000503:physiopathology / Q000821:virology; D008561:Membrane Fusion / Q000187:drug effects*; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D053485:Porcine epidemic diarrhea virus / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D011499:Protein Processing, Post-Translational / Q000187:drug effects*; D011991:Receptors, Virus / Q000378:metabolism*; D064370:Spike Glycoprotein, Coronavirus; D014357:Trypsin / Q000494:pharmacology*; D014709:Vero Cells; D014759:Viral Envelope Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D008562:Membrane Glycoproteins; D011991:Receptors, Virus; D064370:Spike Glycoprotein, Coronavirus; D014759:Viral Envelope Proteins; C578557:spike glycoprotein, SARS-CoV; C578553:spike protein, mouse hepatitis virus; D014357:Trypsin