Metabolic changes in diseased insects: IV. Radioautographic studies on protein changes in nuclear polyhedrosis, densonucleosis, and Tipula iridescent virus infections

Abstract

Changes in glutamic acid, leucine, arginine, and tyrosine in Lepidoptera and Hymenoptera tissues infected with nuclear polyhedrosis (NPV), densonucleosis (DNV), or Tipula iridescent (TIV) viruses were studied by radioautography with a view to determining the effect of the viruses on protein metabolism. During NPV and DNV infection cycles, enlargement of the nucleus was accompanied by an increase in the nucleus and a simultaneous decrease in the cytoplasm of the amino acids. Total cell protein increased at the intermediate stage of infection and then decreased. The rate of change in nuclear protein content was inversely proportional to the rate of change in cytoplasmic protein content. The spindle-shaped cytoplasmic inclusions which characterize the NPV of Lambdina fiscellaria lugubrosa incorporate tritiated glutamic acid, leucine, and tyrosine and stain deeply with Naphthol Yellow S indicating the presence of lysine, arginine, and histidine. The inclusions are produced in L. f. lugubrosa infected by the NPV of Caripeta divisata and Orgyia pseudotsugata but not in the latter two insect species infected by homologous virus. Changes in amino acids of tissues infected with TIV differed from those described above in that an increase in total cell arginine was maintained up to the advanced stage of viral pathogenesis. There was very little change in rate of nuclear or cytoplasmic protein content during the infection cycle.