Ultrastructural Evidence for the Cellular Uptake of Rotavirus by Endocytosis

The ultrastructural aspects of rotavirus SA11 infection were studied in MA104 cells, with particular attention directed to the early stages of virus adsorption and penetration. Within the first few minutes postadsorption, rotavirus was seen at the plasma membrane, associated with coated pits and coated vesicles, indicating that SA11 virus is taken into the cell by adsorptive or receptor-mediated endocytosis. Multiple virus particles were seen, beginning at 1 h and continuing throughout infection, in lysosome-like structures. Ultrastructural evidence was obtained to support the hypothesis that rotavirus progeny acquire a temporary envelope by budding into cisternae of the rough endoplasmic reticulum.