title: Characterization of self-assembled virus-like particles of human polyomavirus BK generated by recombinant baculoviruses.
abstract: The major structural protein of the human polyomavirus BK (BKV), VP1, was expressed by using recombinant baculoviruses. A large amount of protein with a molecular mass of about 42 kDa was synthesized and identified by Western blotting. The protein was detected exclusively in the nuclei by immunofluorescent analysis and it was released into culture medium. The expressed BKV VP1 protein was self-assembled into virus-like particles (BK-VLPs) with two different sizes (50 and 26 nm in diameter), which migrated into four different bands in CsCl gradient with buoyant densities of 1.29, 1.30, 1.33, and 1.35 g/cm(3). The immunological studies on the BK-VLPs suggested that they have similar antigenicity with those of authentic BKV particles. Cryoelectron microscopy and 3D image analysis further revealed that the larger BK-VLPs were composed of 72 capsomers which all were pentamers arranged in a T = 7 surface lattice. This system provides useful information for detailed studies of viral morphogenesis and the structural basis for the antigenicity of BKV.
authors.affiliation: Department of Virology II, National Institute of Infectious Diseases, 162-8640, Tokyo, Japan.
authors.forename: Tian-Cheng
authors.initials: TC
authors.lastname: Li
authors.forename: Naokazu
authors.initials: N
authors.lastname: Takeda
authors.forename: Kenzo
authors.initials: K
authors.lastname: Kato
authors.forename: Josefina
authors.initials: J
authors.lastname: Nilsson
authors.forename: Li
authors.initials: L
authors.lastname: Xing
authors.forename: Lars
authors.initials: L
authors.lastname: Haag
authors.forename: R Holland
authors.initials: RH
authors.lastname: Cheng
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Miyamura
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001739:BK Virus / Q000737:chemistry / Q000502:physiology* / Q000648:ultrastructure; D016367:Baculoviridae / Q000235:genetics*; D002213:Capsid / Q000737:chemistry; D036022:Capsid Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D003001:Cloning, Molecular; D020285:Cryoelectron Microscopy; D003470:Culture Media; D005822:Genetic Vectors; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007313:Insecta; D008958:Models, Molecular; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011994:Recombinant Proteins / Q000096:biosynthesis; D019065:Virus Assembly
chemical_list: D036022:Capsid Proteins; D003470:Culture Media; D011994:Recombinant Proteins; C062481:VP1 protein, polyomavirus