Lesions in clinically healthy cattle persistently infected with the virus of bovine viral diarrhea--glomerulonephritis and encephalitis.

Four clinically healthy cattle persistently infected with the virus of bovine viral diarrhea were examined for viral antigen and lesions. Antigen was seen by direct immunofluorescence in cytoplasm of the neurons of the brain and cervical part of the spinal cord, cells and basement membrane of renal glomeruli, reticular cells of lymph nodes and spleen, epithelial cells of small intestinal crypts and renal and testicular tubules, and endothelial cells of blood vessels. Infected neurons were pyknotic and surrounded by astrocytes and macrophages. A few blood vessels in the brains were cuffed with mononuclear cells. Basement membranes of renal glomeruli were irregularly thick with eosinophilic material, and mesangial cells in the glomeruli were plentiful. The virus had a direct effect on some tissues, but was restricted in its cytopathogenicity and was not eliminated by defense mechanisms of the host. Renal glomerular lesions were believed to have an immunologic basis.