Serological classification of avian adenoviruses

One hundred and sixty-seven agents recovered from domestic hens using chick kidney cell cultures were identified as adenoviruses and cross neutralization tests showed that they belong to 7 serological types. Cross neutralization tests between our agents and the 8 serotypes of avian adenovirus recovered in Japan indicated that 6 of our “prototype” strains were closely related to the Japanese agents (which included strains similar to CELO and GAL) whereas one strain (764) was serologically distinct. Electron microscopic examination, physico-chemical tests and gel precipitation tests confirm that strain 764 is an adenovirus and that it has an antigen which is common to the avian adenoviruses but does not cross-react with that of the mammalian agents. We conclude that strains of avian adenoviruses other than CELO and GAL are more widespread than is commonly assumed and that a numbering system for the various serotypes would be useful.