Synthesis in Escherichia coli and immunological characterization of a polypeptide containing the cleavage sites associated with trypsin enhancement of rotavirus SA11 infectivity.

About 45% of the rotavirus SA11 VP3 gene was inserted into a thermoinducible expression plasmid under the control of phage lambda PL promoter. The primary translation product predicted on the basis of the plasmid construction was a hybrid protein in which the 98 amino-terminal amino acids of phage MS2 polymerase were followed by amino acids 42 to 387 of the VP3 protein, which included the region containing the cleavage sites associated with trypsin enhancement of infectivity. On induction, a polypeptide that had the expected mol. wt. and contained VP3-related amino acid sequences as judged by immunological criteria, was synthesized to a level representing about 15% of the total bacterial protein. When a bacterial lysate enriched for the fusion polypeptide was injected into mice, it induced antibodies which inhibited haemagglutination and neutralized SA11 rotavirus infectivity.