Protease activity associated with the capsule protein of Estigmene acres granulosis virus.

The polypeptide composition of a granulosis virus of Estigmene acrea was determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Enveloped nucleocapsids are made up of 24 polypeptides with molecular weights ranging from 11,000 to 98,000. Virus capsule protein contains protease activity which degrades capsule protein from 30,000 to 25,000 through two intermediates of 29,000 and 27,000. The putative endoprotease is active at alkaline pH, sensitive to heat and diethylpyrocarbonate inhibition, and resistant to 10(-3) M phenylmethylsulfonyl fluoride. No alteration in the electrophoretic pattern of viral structural proteins was detected in virus preparations containing endoproteolytic activity. A low level of alkaline exoprotease activity associated with capsule protein was also detected.