Effect of tunicamycin on rotavirus assembly and infectivity

Bovine rotavirus grown in the presence or absence of tunicamycin was analyzed with respect to yield of infectious virus, the ratio of complete to incomplete particles, and polypeptide composition. Tunicamycin at a concentration of 1 microgram/ml reduced virus yields by 4 logs and completely prevented the incorporation of [3H]uridine into complete rotavirus particles, as determined by cesium chloride gradient analysis. Concomitant with a reduction in complete particles, three rotavirus polypeptides shifted in their relative position on polyacrylamide gels from 41,900-molecular-weight position (41.9K), 29.3K, and 16.1K to migrate at 35.5K, 22.7K, and 15.5K, respectively. Limited proteolysis indicated that the lower-molecular-weight polypeptides possessed the same constituent peptides as the larger polypeptides, suggesting that they represented the unglycosylated equivalents. These results suggest that interference with glycosylation prevents proper assembly of the outer coat proteins in bovine rotavirus.