Experimentally induced respiratory syncytial viral infection in lambs.

Signs of clinical illness, lesions, and seroconversion were observed in lambs experimentally inoculated with a respiratory syncytial virus of bovine origin. Signs of clinical illness were mild and consisted of fever and hyperpnea. Multifocal areas of interstitial pneumonia were seen in lambs necropsied during the period of clinical response. All lambs seroconverted to viral antigen, and the virus was isolated from two of the lambs.