Abstract
Two cytopathogenic agents were isolated in horse kidney cell cultures from the bronchus and lung of a three-month-old Thoroughbred colt with pneumonia presumed to be caused by bacterial infection. They were propagated in equine fetal dermis cells with cytopathogenic effect and development of intranuclear inclusions similar to those in primary horse kidney cell cultures. The isolate from the pneumonic lesion was used as a representatiVe for characterization, because both isolates were identical in the cross serum neutralization (SN) test. The isolate was found to contain DNA because of its replication inhibited by 5-iodo-2'-deoxyuridine. Its buoyant density was 1.29 g/cm3. The virion had a cubic symmetry without envelope, and measured approximately 74 nm in diameter. The virus was resistant to chloroform and ether. It was slightly inactivated at pH 3.0 for 3 hours. Hemagglutination was observed in human (type O), guinea pig, horse and rat erythrocytes. The equine isolate shared a common complement-fixing antigen with a canine adenovirus, but it did not react with this virus in the SN test. A serologic survey on a stud from which the foal in the present study was derived demonstrated a prevalence of adenoviral infection.
