Identification of rotavirus particle types.
Negative-contrast electron microscopy of purified rotavirus particles reveals two particle types: single-shelled and double-shelled particles. The relationship of these particle types, seen by negative staining, to the enveloped and various types of nonenveloped particles seen in thin sections of virus-infected cells was determined. Thin-section and negative-contrast electron microscopic analyses were performed on cell lysates from simian rotavirus. SA11-infected cells and on highly purified double- and single-shelled particles. In thin sections, double-shelled particles appeared as smooth-edged ovals containing dense nucleoids, whereas single-shelled particles had ragged edges and threads of material extending from their centers. The majority of nonenveloped particles seen in thin sections of infected cells were identified as double-shelled particles. Enveloped particles showed typical membrane structure and were observed rarely in crude rotavirus stocks, although they constitute about 10% of the particles within infected cells. It is hypothesized that the enveloped form is a transient one and the envelope is lost in the endoplasmic reticulum of the host cells. Finally, the 50-55 nm type IV particles seen within lysosome-like bodies in infected cells were identified as subviral particles formed from input virions.
D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D004721:Endoplasmic Reticulum; D000882:Haplorhini; D006801:Humans; D008854:Microscopy, Electron; D009024:Morphogenesis; D012087:Reoviridae / Q000648:ultrastructure*; D012401:Rotavirus / Q000302:isolation & purification / Q000648:ultrastructure*