Adenovirus Infection and Disease. II. Histopathology of Natural and Experimental Disease

SUMMARY Adenovirus infection in chickens has been associated with a drop in production and problems of egg-shell quality. Gross lesions associated with the disease have been tracheitis and hepatitis. The hepatitis was characterized histologically as lymphocytic foci containing a few heterophils early in the disease. Focal fibrinoid necrosis was present, occasionally with a granulomatous response accompanied by fatty infiltration. The lesion progressed to fibrosis and hyperplasia of the bile duct. The tracheitis varied in severity and consisted of a round-cell infiltrate into the lamina propria. In addition to the segmental infiltrate, lymphoid follicle formation was prominent. Susceptible embryos inoculated with the virus were stunted and dwarfed. The gross lesions were those of hepatitis. Histologically, eosinophilic intranuclear inclusion bodies were present in the hepatocytes. A portal inflammatory cell infiltrate composed of heterophils and fibroblastic cells was observed 4 days postinoculation. Chickens 3 days to 8 weeks old were inoculated with the cloned virus. Tracheitis and hepatitis were present at necropsy. The microscopic lesions were identical to those in field cases with one exception: a necrotizing pancreatitis observed occasionally in the experimental chickens is not found in the naturally occurring disease.