title: JC virus intranuclear inclusions associated with PML-NBs: analysis by electron microscopy and structured illumination microscopy.
abstract: Progressive multifocal leukoencephalopathy is a fatal demyelinating disorder caused by JC virus infection. JC virus was recently found to target promyelocytic leukemia nuclear bodies (PML-NBs), punctuate domains in the nuclei. Thus, the virus progenies cluster in dots as intranuclear inclusions (ie, as dot-shaped inclusions). In the present study, both the viral major and minor capsid proteins were expressed from polycistronic expression vectors with a powerful promoter, and formation into virus-like particles (VLPs) was examined by electron microscopy. When the upstream regulatory sequence including the agnogene (nt 275 to 490) was present, capsid protein expression was suppressed, but numerous VLPs were efficiently formed with restricted accumulation to PML-NBs. VLPs were uniform, and the cells were severely degraded. In contrast, when the 5' terminus of the agnogene (nt 275 to 409; 135 bp) was deleted, capsid protein expression was markedly enhanced, but VLPs were more randomly produced in the nucleus outside of PML-NBs. VLPs were pleomorphic, and cell degradation was minimal. JC virus association with PML-NBs was confirmed in human brain tissues by structured illumination microscopy. PML-NBs were shaped in spherical shells, with viral capsid proteins circumscribing the surface. These findings indicate that PML-NBs are intranuclear locations for pathogenic JC virus proliferation. Either the agnogene or its product likely supports efficient progeny production at PML-NBs, leading to subsequent degeneration of host glial cells.
authors.affiliation: Department of Pathology, Kyorin University School of Medicine, Tokyo, Japan. Electronic address: yhara@ks.kyorin-u.ac.jp.
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Shishido-Hara
authors.affiliation: Research Center for Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Shizuko
authors.initials: S
authors.lastname: Ichinose
authors.affiliation: Laboratory of Structural Neuropathology, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan.
authors.forename: Toshiki
authors.initials: T
authors.lastname: Uchihara
mesh_terms: D036022:Capsid Proteins / Q000648:ultrastructure; D002478:Cells, Cultured; D006801:Humans; D045586:Intranuclear Inclusion Bodies / Q000648:ultrastructure*; D007577:JC Virus / Q000648:ultrastructure*; D015473:Leukemia, Promyelocytic, Acute / Q000473:pathology* / Q000821:virology; D007968:Leukoencephalopathy, Progressive Multifocal / Q000473:pathology*; D008853:Microscopy; D008854:Microscopy, Electron; D014162:Transfection; D014771:Virion / Q000648:ultrastructure
chemical_list: D036022:Capsid Proteins