Abstract
By means of disc electrophoresis, the midgut proteins of the healthy silkworm larvae, Bombyx mori L., and of the diseased larvae infected with the cytoplasmic-polyhedrosis virus were separated in the acrylamide gel, and the two patterns were compared. Midgut proteins of the healthy larvae, in the middle stage of the 5th instar, were resolved into more than 17 fractions. In the earlier stages of the virus infection, the protein pattern in the diseased midgut was quite similar to that of the healthy midgut, quantitatively as well as qualitatively. However, in the protein electropherogram of the diseased midgut, 2 or 3 days after the virus infection, an additional band appered very close to the origin. This disease-specific fraction was confirmed to be corresponding to a polyhedron protein, increasing in its concentration as the disease advanced. Even in the heavily diseased midgut, the general pattern and the concetration of protein fractions except polyhedron protein band were almost similar to those of the healthy midgut, only that some faster migrating bands in the diseased midgut slightly decreased in the concentration. This might be a reflection that the protein metabolism in the host tissue was well maintained homeostatically even under the progress of the viral disease.
