title: Intracellular localization of influenza C virus NS2 protein (NEP) in infected cells and its incorporation into virions.
abstract: RNA segment 7 of influenza C virus encodes two non-structural (NS) proteins, NS1 and NS2. The influenza C virus NS2 protein has been proposed to possess nuclear export activity like that of influenza A and B virus NS2 proteins (NEP). In the present study, we investigated the kinetics and localization of the NS2 protein in influenza C virus-infected cells, and analysed whether NS2 is present in virions. Immunofluorescent staining analysis of the infected cells indicated that NS2 was localized in the nucleus immediately after synthesis and predominantly in the cytoplasm in the later stages of infection. Confocal microscopy revealed that a part of the NS2 protein was colocalized with nucleoprotein NP/vRNP in the cytoplasm and on the cell membrane in the late stages of infection. The NS2 protein was detected in influenza C virions purified by gradient centrifugations and/or affinity chromatography. Trypsin treatment demonstrated that the NS2 protein was present inside the viral envelope. Furthermore, glycerol gradient analysis of detergent-solubilized virions revealed that the NS2 protein cosedimented with vRNPs. These data suggest that the influenza C virus NS2 protein is incorporated into virions, where it associates with vRNP.
authors.affiliation: Department of Bacteriology, Faculty of Medicine, Yamagata University, Iida-Nishi, Yamagata 990-9585, Japan.
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Kohno
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Muraki
authors.forename: Yoko
authors.initials: Y
authors.lastname: Matsuzaki
authors.forename: Emi
authors.initials: E
authors.lastname: Takashita
authors.forename: Kanetsu
authors.initials: K
authors.lastname: Sugawara
authors.forename: Seiji
authors.initials: S
authors.lastname: Hongo
mesh_terms: D021581:Active Transport, Cell Nucleus; D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D002642:Chick Embryo; D003593:Cytoplasm / Q000378:metabolism; D006801:Humans; D007251:Influenza, Human / Q000378:metabolism* / Q000821:virology; D009982:Gammainfluenzavirus / Q000378:metabolism*; D012261:Ribonucleoproteins / Q000378:metabolism; D017361:Viral Nonstructural Proteins / Q000378:metabolism*; D014771:Virion / Q000378:metabolism*; D014779:Virus Replication
chemical_list: D012261:Ribonucleoproteins; D017361:Viral Nonstructural Proteins