Effect of trypsin and chymotrypsin on polypeptides of human rotavirus KUN strain.

In view of the fact that trypsin enhances the infectivity of human rotavirus and decreases its hemagglutination, the trypsin-mediated structural modification of the viral polypeptides was analysed, using the KUN strain, a cultivable human rotavirus isolate, grown in the absence of trypsin. A major polypeptide sensitive to trypsin treatment was Vp4 with a molecular weight of 80,000, being cleaved into three polypeptides with molecular weights of 54,000 (P54), 30,000 (P30), and 24,000 (P24). Vp4 was also sensitive to chymotrypsin treatment, generating cleavage products different from those obtained with trypsin.