The genes of the Dearing strain of reovirus serotype. 3, which consist of double-stranded RNA, have been cloned into pBR322 by tailing both strands ofeach gene with poly(A), transcribing them with reverse transcriptase, self-hybridizing the cognate plus and minus cDNA strands, incubating them with Ekcherichia coli DNA polymerase I to ensure that they are complete, and cloning the double-stranded cDNA molecules by standard procedures. The sequence of the cloned S2 gene has been determined. The sequences at the termini are exactly the same as those at the ends of the native double-stranded RNA gene.

The 38,200-molecular weight (unreduced)/41,900-molecular-weight (reduced) glycoprotein of bovine rotavirus, isolate C486, was identified as the major neutralizing antigen. This glycoprotein as well as the corresponding glycoprotein of another bovine rotavirus serotype also specifically attached to cell monolayers under normal conditions for virus adsorption in vitro. Further support for this glycoprotein being directly responsible for virus attachment to cells was that (i) infectious virus of both serotypes could compete with the C486 glycoprotein for cell surface receptors, and (ii) neutralizing monospecific antiserum and neutralizing monoclonal antibodies directed toward the glycoprotein could block this virus-cell interaction. Preliminary epitope mapping of the glycoprotein with monoclonal antibodies further localized the neutralization-adsorption domain to a peptide with an approximate molecular weight of 14,000. The effect of two protein modifications, glycosylation and disulfide bridging, on the reactivity of this peptide with antibodies and cell surface receptors was investigated. It was demonstrated that, whereas glycosylation did not appear to affect these reactivities, disulfide bridging seemed to be essential.

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