title: Biochemical and functional analysis of the Borna disease virus G protein.
abstract: The Borna disease virus (BDV) antigenome is comprised of five major open reading frames (ORFs). Products have been reported only for ORFs I, II, and III, encoding N (p40), P (p24/p23), and M (gp18), respectively. ORF IV predicts a 57-kDa protein with several potential glycosylation sites. Analysis of radiolabeled extracts from BDV-infected C6 cells and BHK-21 cells transfected with a Semliki Forest virus vector that contains ORF IV demonstrated the presence of a 94-kDa protein (G protein) which was sensitive to tunicamycin, endoglycosidase F/N-glycosidase, and endoglycosidase H but not to O-glycosidase. Sera from BDV-infected rats detected the G protein and had neutralization activity that was reduced following immunoadsorption with the G protein. Preincubation of cells with the G protein interfered with BDV infectivity. This effect was enhanced by treatment of the G protein with the exoglycosidase alpha-mannosidase and reduced after subsequent treatment with N-acetyl-beta-D-glucosaminidase. In concert these findings indicate that ORF IV encodes a 94-kDa N-linked glycoprotein with extensive high mannose- and/or hybrid-type oligosaccharide modifications. The presence of neutralization epitopes on the G protein and its capacity to interfere with infectivity suggest that the G protein is important for viral entry.
authors.affiliation: Department of Microbiology and Molecular Genetics, University of California-Irvine, 92697-4290, USA.
authors.forename: P A
authors.initials: PA
authors.lastname: Schneider
authors.forename: C G
authors.initials: CG
authors.lastname: Hatalski
authors.forename: A J
authors.initials: AJ
authors.lastname: Lewis
authors.forename: W I
authors.initials: WI
authors.lastname: Lipkin
mesh_terms: D000818:Animals; D000956:Antigens, Viral / Q000737:chemistry* / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D001891:Borna disease virus / Q000378:metabolism*; D002460:Cell Line; D006224:Cricetinae; D000939:Epitopes / Q000276:immunology; D015870:Gene Expression; D005822:Genetic Vectors; D006023:Glycoproteins / Q000737:chemistry* / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D009500:Neutralization Tests; D016366:Open Reading Frames; D011817:Rabbits; D051381:Rats; D011917:Rats, Inbred Lew; D012672:Semliki forest virus / Q000235:genetics; D014407:Tumor Cells, Cultured; D014764:Viral Proteins / Q000737:chemistry* / Q000235:genetics / Q000276:immunology / Q000378:metabolism
chemical_list: D000956:Antigens, Viral; D000939:Epitopes; D006023:Glycoproteins; D014764:Viral Proteins