title: Outer-capsid P8 proteins of phytoreoviruses mediate secretion of assembled virus-like particles from insect cells.
abstract: Phytoreoviruses are composed of two concentric capsid layers that surround a viral genome. The capsids are formed mainly by the inner-capsid P3 protein and the outer-capsid P8 protein. During the infection of insect-vector cells, these play important roles in packaging the viral genome and the enzymes required for its transcription. P3 and P8 proteins, when co-expressed in Spodoptera frugiperda cells, co-localized in cells and were released as spherical clusters. In contrast P3 proteins expressed in the absence of P8 protein were associated with the cells when they were examined by confocal microscopy. Cryo-electron microscopy revealed that the secreted clusters, composed of P3 and P8 proteins, were double-layered virus-like particles that were indistinguishable from intact viral particles. Our results indicate that P8 proteins mediate the secretion of assembled virus-like particles from S. frugiperda insect cells and, therefore, most probably from insect-vector cells also.
authors.affiliation: National Agricultural Research Center, Tsukuba, Ibaraki 305-8666, Japan. naomiyazaki@protein.osaka-u.ac.jp
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Miyazaki
authors.forename: Kyoji
authors.initials: K
authors.lastname: Hagiwara
authors.forename: Taiyun
authors.initials: T
authors.lastname: Wei
authors.forename: Hongyan
authors.initials: H
authors.lastname: Chen
authors.forename: Atsushi
authors.initials: A
authors.lastname: Nakagawa
authors.forename: Li
authors.initials: L
authors.lastname: Xing
authors.forename: R Holland
authors.initials: RH
authors.lastname: Cheng
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Omura
mesh_terms: D000818:Animals; D036022:Capsid Proteins / Q000378:metabolism*; D002460:Cell Line; D020285:Cryoelectron Microscopy; D018613:Microscopy, Confocal; D012087:Reoviridae / Q000502:physiology*; D018411:Spodoptera; D014764:Viral Proteins / Q000378:metabolism; D022701:Virosomes / Q000378:metabolism; D057074:Virus Release
chemical_list: D036022:Capsid Proteins; D014764:Viral Proteins; D022701:Virosomes