title: Mutation in the cytoplasmic retrieval signal of porcine epidemic diarrhea virus spike (S) protein is responsible for enhanced fusion activity.
abstract: Murine-adapted porcine epidemic diarrhea virus (PEDV), MK-p10, shows high neurovirulence and increased fusion activity compared with a non-adapted MK strain. MK-p10 S protein had four mutations relative to the original virus S, and one of these (H→R at position 1381, H1381R) in the cytoplasmic tail (CT) was suggested to be responsible for the increased fusion activity. To explore this, we examined fusion activity using recombinant S proteins. We expressed and compared the fusion activity of MK-p10 S, S with the H1381R mutation, S with the three other mutations that were not thought to be involved in high fusion activity, and the original S protein. The MK-p10 and MK-H1381R S proteins induced larger cell fusions than others. We also examined the distribution of these S proteins; the MK-p10 and MK-H1381R S proteins were transported onto the cell surface more efficiently than others. These findings suggest that the H1381R mutation is responsible for enhanced fusion activity, which may be attributed to the efficient transfer of S onto the cell surface. H1381 is a component of the KxHxx motif in the CT region, which is a retrieval signal of the S protein for the endoplasmic reticulum-Golgi intermediate compartment (ERGIC). Loss of this motif could allow for the efficient transfer of S proteins from ERGIC onto the cell surface and subsequent increased fusion activity.
authors.affiliation: Laboratory of Acute Respiratory Viral Diseases and Cytokines, Department of Virology III, National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashimurayama, Tokyo 208-0011, Japan.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Shirato
authors.forename: Madoka
authors.initials: M
authors.lastname: Maejima
authors.forename: Shutoku
authors.initials: S
authors.lastname: Matsuyama
authors.forename: Makoto
authors.initials: M
authors.lastname: Ujike
authors.forename: Ayako
authors.initials: A
authors.lastname: Miyazaki
authors.forename: Natsumi
authors.initials: N
authors.lastname: Takeyama
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Ikeda
authors.forename: Fumihiro
authors.initials: F
authors.lastname: Taguchi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D018352:Coronavirus Infections / Q000662:veterinary* / Q000821:virology; D003593:Cytoplasm / Q000821:virology; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D053485:Porcine epidemic diarrhea virus / Q000235:genetics* / Q000502:physiology; D021382:Protein Sorting Signals; D021381:Protein Transport; D064370:Spike Glycoprotein, Coronavirus; D013552:Swine; D013553:Swine Diseases / Q000821:virology*; D014759:Viral Envelope Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D053586:Virus Internalization
chemical_list: D008562:Membrane Glycoproteins; D021382:Protein Sorting Signals; D064370:Spike Glycoprotein, Coronavirus; D014759:Viral Envelope Proteins; C578557:spike glycoprotein, SARS-CoV; C578553:spike protein, mouse hepatitis virus