Virus-related diabetes in cattle

Abstract

Twelve cattle with IDDM presented emaciation, polyuria, polydipsia, glycosuria, persistent hyperglycemia, and decreased glucose tolerance. In chronic cases, major histopathological findings in the pancreas were a decrease in the size and number of pancreatic islets, interlobular and interacinar fibrosis, mild lymphocytic insulitis, and vacuolation of a few islets. Cells comprising atrophic islets were immunohistochemically revealed to be a-and d-cells. In acute cases, most islets consisted of vacuolated and severely degranulated b-cells and also contained numerous necrotic cells. Lymphocytic insulitis was common. Bovine IgG-immunoreactive islet cells were seen frequently in the vacuolated islets. Atrophic and vacuolated islets had no or small numbers of granules immunoreactive to GAD, respectively. In seven cases the bovine viral diarrhea virus was sought. Noncytopathic virus was isolated from blood leukocytes and sera of all cases. Viral antigen was demonstrated immunohistochemically in the acinar cells of the exocrine pancreas and epithelial cells of the pancreatic ducts. In four cases, viral antigen was also recognized in the islet cells. The results suggest that autoimmune insulin-dependent diabetes may have been induced by persistent BDV infection, resulting in the gradual and selective destruction of b-cells in pancreatic islets.