Origin of an alkaline protease associated with the capsule of a granulosis virus of the armyworm, Pseudaletia unipuncta (Haworth).

The larval digestive juice of the armyworm, Pseudaletia unipuncta (Haworth), has extremely high alkaline protease activity. No protease or negligible protease activity is present in the hemolymph and in extracts of the body wall. The digestive juice protease is absorbed by the capsules of a granulosis virus under low ionic condition. The protease degrades the capsule matrix proteins at alkaline conditions. The absorption of digestive juice protease by capsules occurs when capsules are obtained by triturating the whole infected larvae. On the other hand, capsules, which have been collected from the triturated body walls of infected larvae whose digestive tracts have been removed, are not degraded when the incubation in an alkaline solution is for less than 24 hours at 25 degrees C. The results suggest that the protease associated with the capsule is derived from the digestive juice of the insect.