Ultrastructural study of rotavirus replication in cultured cells

A systematic ultrastructural analysis of the replication cycle of the simian rotavirus SA11 in permissive MA104 cells was performed under reproducible conditions. At 8 h p.i., small areas of viroplasm were seen adjacent to swollen vesicles of the rough endoplasmic reticulum (rer) containing a few 80 to 90 nm virus particles. At later times, the size and number of these inclusions increased and the rer contained large numbers of the 80 to 90 nm particles as well as 52 to 65 nm particles. Infected cells eventually lysed, releasing progeny virus. Other cytological alterations included virus particles sequestered in lysosome-like bodies, 15 to 20 nm tubular structures in the nucleus and/or cytoplasm, convoluted membranes within the rer, filament bundles associated with virus particles, and mitochondria containing 1 to 5 virus particles. In addition, SA11 replication was studied in several less permissive cell lines. The results were similar to those with MA104 cells except that a smaller percentage of the cells were productively infected.