[Study of Sendai virus proteins: the proteolytic activity in the composition of the viral particles].

Disruption of virions with non-ionic detergent induced cleavage of virus proteins in purified preparations of Sendai virus. The proteolytic activity was detected in fraction of both the soluble proteins and subvirus particles. In the fraction of soluble proteins which initially had contained glycoproteins of the viral external envelope--HN and F--, both proteins were cleaved at a different relative rate. In parallel with polypeptide cleavage, the hemagglutinating and neuraminidase activity of the analysed specimens decreased. In the fraction of subvirus particles, sequential cleavage of inner virion proteins, P, m1, M, and NP, was observed, and also the formation of certain classes of intermediate products which had two typical features; (1) the products retained their connection with subvirus particles, and (2) the products of hydrolysis of the major structural proteins of the internal virus ribonucleoprotein, --P and NP--, had the electrophoretic motility similar to that of minor components, m2--m5. These observations demonstrate the principal possibility of the origin of some minor Sendai virus proteins as a result of degradation of major virus proteins.