title: Intercellular gamma-herpesvirus dissemination involves co-ordinated intracellular membrane protein transport.
abstract: The murine gamma-herpesvirus-68 (MHV-68) ORF27 encodes gp48, a type 2 transmembrane glycoprotein that contributes to intercellular viral spread. Gp48 is expressed on the surface of infected cells but is retained intracellularly after transfection. In this study, we show that the multimembrane spanning ORF58 gene product is both necessary and sufficient for gp48 to reach the cell surface. ORF58-deficient MHV-68 expressed ORF27 in normal amounts, but retained it in the endoplasmic reticulum (ER). Transfected ORF27 also remained in ER, whereas green fluorescent protein-tagged ORF58 localized to the ER and trans-Golgi network. When ORF27 and ORF58 were co-transfected, they formed a protein complex and reached the cell surface. Surprisingly, ORF58 rather than ORF27 mediated cell binding via a small extracellular loop. The heavily glycosylated ORF27 component of the complex may, therefore, act mainly to protect this loop against antibody. The interdependent transport of ORF27 and ORF58 transport ensures that such protection is always present.
authors.affiliation: Division of Virology, Department of Pathology, University of Cambridge, Cambridge, UK.
authors.forename: Janet S
authors.initials: JS
authors.lastname: May
authors.forename: Brigitte D
authors.initials: BD
authors.lastname: de Lima
authors.forename: Susanna
authors.initials: S
authors.lastname: Colaco
authors.forename: Philip G
authors.initials: PG
authors.lastname: Stevenson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism; D002460:Cell Line; D006224:Cricetinae; D004721:Endoplasmic Reticulum / Q000648:ultrastructure / Q000821:virology; D005347:Fibroblasts / Q000648:ultrastructure / Q000821:virology; D019084:Fluorescent Antibody Technique, Indirect; D006023:Glycoproteins / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D007425:Intracellular Membranes / Q000378:metabolism* / Q000648:ultrastructure; D007668:Kidney / Q000166:cytology / Q000196:embryology; D051379:Mice; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D009154:Mutation; D041681:NIH 3T3 Cells; D011233:Precipitin Tests; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D018144:Rhadinovirus / Q000235:genetics* / Q000502:physiology; D014764:Viral Proteins / Q000737:chemistry / Q000502:physiology*; D014779:Virus Replication
chemical_list: D000911:Antibodies, Monoclonal; D006023:Glycoproteins; D014764:Viral Proteins