title: Rotavirus-induced fusion from without in tissue culture cells.
abstract: We present the first evidence of fusion from without induced in tissue culture cells by a nonenveloped virus. Electron micrographs of two strains of rotavirus, bovine rotavirus C486 and rhesus rotavirus, show that virally mediated cell-cell fusion occurs within 1 h postinfection. Trypsin activation is necessary for rotavirus to mediate cell-cell fusion. The extent of fusion is relative to the amount of virus used, and maximum fusion occurs between pHs 6.5 and 7.5. Fusion does not require virus-induced protein synthesis, as virus from both an empty capsid preparation and from an EDTA-treated preparation, which is noninfectious, can induce fusion. Incubation of rotavirus with neutralizing and nonneutralizing monoclonal antibodies before addition to cells indicates that viral protein 4 (VP4; in the form of VP5* and VP8*) and VP7 are involved in fusion. Light and electron micrographs document this fusion, including the formation of pores or channels between adjacent fused cells. These data support direct membrane penetration as a possible route of infection. Moreover, the assay should be useful in determining the mechanisms of cell entry by rotavirus.
authors.affiliation: Centre for Food and Animal Research, Agriculture Canada, Ottawa, Ontario.
authors.forename: M M
authors.initials: MM
authors.lastname: Falconer
authors.forename: J M
authors.initials: JM
authors.lastname: Gilbert
authors.forename: A M
authors.initials: AM
authors.lastname: Roper
authors.forename: H B
authors.initials: HB
authors.lastname: Greenberg
authors.forename: J S
authors.initials: JS
authors.lastname: Gavora
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D002213:Capsid / Q000502:physiology*; D036022:Capsid Proteins; D002417:Cattle; D002459:Cell Fusion; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology / Q000648:ultrastructure; D002522:Chlorocebus aethiops; D002784:Cholesterol / Q000494:pharmacology; D004492:Edetic Acid / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007668:Kidney; D007700:Kinetics; D008253:Macaca mulatta; D008854:Microscopy, Electron; D012401:Rotavirus / Q000502:physiology*; D013045:Species Specificity
chemical_list: D000911:Antibodies, Monoclonal; D036022:Capsid Proteins; C060339:VP4 protein, Rotavirus; D002784:Cholesterol; D004492:Edetic Acid