Characterization of binding of simian rotavirus SA-11 to cultured epithelial cells.

Rotavirus causes enteritis in both man and animals. The identity of the rotavirus receptor is not known. The nature of the binding interaction and the relationship between virus binding and internalization have not previously been reported. We studied the binding of [5,6-3H]uridine-labeled rotavirus SA11 to confluent monolayers of MA104 cells. We found approximately 13,000 receptor units per cell. The binding was sodium-dependent, pH-insensitive between 5.5 and 8, independent of added calcium, and dependent on sialic acid residues in the membrane. It could be inhibited by mucin. These features may provide clues to the identity of the receptor. Virus was not internalized to significant extent at 4 degrees C. After warming to 37 degrees C, virus was internalized over about 60 min. All binding sites appeared to be equally internalizable. The techniques developed to distinguish between binding and internalization may help to elucidate the mechanism of internalization.