Pathophysiology of nitrogen catabolism in the midgut of silkworm, Bombyx mori L.(Lepidoptera: Bombycidae), infected with a cytoplasmic-polyhedrosis virus

The effect of an infection of a cytoplasmic-polyhedrosis virus (CPV) in the silkworm, Bombyx mori, on the uric acid content of the midgut and of the feces was studied. In an infected midgut, the uric acid content increased greatly after the 3rd day of virus ingestion, and at a late stage, it increased to a value five times that of an unifected midgut. Incorporation of 14C-glycine, which had been injected hemocoelically, into uric acid in the infected midgut was much faster and in a larger quantity than that in the uninfected midgut. As for the faces, the uric acid content in those obtained from an infected larva was maintained at a much higher value throughout the polyhedrosis than that of feces from an uninfected larva.The results indicated that a high level of nitrogen catabolism was induced in the midgut by an infection of CPV, and a great amount of uric acid was excreted with the feces and the disease progressed.