Effects of cyclosporine A on reovirus-infected broilers.

The effect of cyclosporine A on reovirus-infected male broiler chickens was studied. Beginning at 1 or 10 days of age, 3 groups of 15 broilers were injected in the pectoral muscle with 50 mg of cyclosporine A (CSA) in oil per kg body weight every 3 days until 28 days. Controls were injected with olive oil. Two CSA-injected groups and one untreated group were orally infected with 1000 TCID50 of reovirus at 1 day of age. Cell-mediated immunity was evaluated at 17 and 24 days by a delayed-wattle-response test to injected phytohemagglutinin (PHA-M). Cyclosporine A and reovirus significantly (P less than 0.001) depressed the wattle response following the first injection of PHA-M but not the second. At necropsy 28 days postinoculation (PI), no gross lesions were apparent. Histologic lesions in birds infected with reovirus were lymphocytic pericarditis and tenosynovitis; synovial cells were hyperplastic, and heterophils and fibrin were in synovial spaces. Thymic medullary diameters were significantly (P less than 0.001) smaller in all CSA-treated birds. Although CSA suppressed cell-mediated immunity somewhat, there were no apparent differences in severity of microscopic lesions among reovirus-infected groups.