T antigens of bovine and canine adenoviruses demonstrated by immunofluorescence.

The intracellular development in acutely infected cells of bovine and canine adenovirus T antigens was followed by immunofluorescent staining. With both species of adenovirus, antigen was first detected as intranuclear pin-points at 18 hr postinfection and coalescence into large lobular masses was noticed by 24 hr. Cross-reactions between bovine 1 (nononcogenic) and bovine 3 (oncogenic) T antigens were not observed by the direct technique although the more sensitive indirect procedure did reveal cross-reactivity. Extensive cross-reactions were observed between the T antigens of the oncogenic canine hepatitis virus and the "nononcogenic" Toronto strain of canine adenovirus. The magnitude of these reactions places the two canine strains in the same T antigen subgroup. The canine and bovine T antigens were not stained by tumor antisera against any of the known human or simian T antigen subgroups. Antigen synthesis was not prevented by inhibitors of deoxyribonucleic acid synthesis although the appearance was altered markedly.