Synthesis in Escherichia coil and Immunological Characterization of a Polypeptide Containing the Cleavage Sites Associated with Trypsin Enhancement of Rotavirus SAIl Infectivity

About 45 % of the rotavirus SAil 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 mino 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 xpected tool. wt. and contained VP3-related amino acid sequences as judged by immunological criteria, w s synthesized toa level representing about 15 % of the total bacterial protein. When a bacterial lysate nriched for the fusion polypeptide was injected into mice, it induced antibodies which inhibited haemagglutination and neutralized SA11 rotavirus infectivity