The Morphogenesis of a Cytopathic Bovine Rotavirus in Madin-Darby Bovine Kidney Cells

Veterinary Research Laboratories Stormont Belfast BT4 3SD Northern Ireland The morphogenesis of a cytopathic bovine rotavirus isolate was examined in MDBK cells. Distension of cisternae of the rough endoplasmic reticulum was seen 14 h post-infection (p.i.), but few virus particles were present. Many virus particles were observed within distended cisternae of the endoplasmic reticulum 22 h p.i., and matrices of viroplasm were found close to developing virus particles. The virus particles measured 68 to 72 nm in diam. and consisted of an electron-dense nucleoid surrounded by a single less electron-dense shell. In contrast, many of the virus particles observed 54 h p.i. possessed an additional, outer, electron-dense shell. These double-shelled particles were 76 to 82 nm in diam. and acquired the outer shell by a budding process. Virus was released from the cell by discharge through breaks in the plasma membranes of damaged cells. Received 17 May 1976; accepted 12 July 1976.