Viral Encephalomyelitis of Pigeons: Identification and Characterization of the Virus

SUMMARY A new virus was isolated from the brains of pigeons suffering from nervous disorders in Iraq. The isolate grew on the chorioallantoic membrane (CAM) of chick, duck, and turkey embryonated eggs, producing minute pock lesions. The virus grew in chick embryo fibroblast (CEF), duck embryo fibroblast (DEF), and turkey embryo fibroblast (TEF) cells, producing syncytia with both acidophilic and basophilic intranuclear inclusions. Small clear plaques 1-2 mm in diameter also grew on CEF, DEF, and TEF 3-4 days postinoculation. The virus was highly pathogenic to experimentally inoculated pigeons but had no effect on chickens, ducks, turkeys, sparrows, lovebirds, rabbits, guinea pigs, and mice. The virulence of the virus was markedly reduced by the 7th passage in CEF. Replication of the virus was inhibited by BUdR, and its infectivity was greatly reduced by ether and chloroform. Virus infectivity was markedly reduced by 50 C for 10 minutes and moderately affected by pH 4 for one hour. Electron microscopy of negatively stained preparations revealed icosahedral particles, 7090 nm in diameter, with 162 capsomeres. Common precipitating but not neutralizing or complement-fixing antigens were detected between the isolated virus and human herpesviruses I and II. No antigenic relationships were detected with other viruses tested. The isolate is probably a new member of the family Herpesviridae.