[Immunofluorescent diagnosis of bovine adenoviruses]

By applying the direct immunofluorescent method, a study was carried out on the appearance and accumulation of adenoviral antigen in cattle, in infected cellular cultures from the testes of calves and in epithelial cell obtained by smearing with nasal mucosa and conjunctiva of experimentally infected and spontaneously taken ill with adenoviral infection calves. A specific conjugate was obtained by the writers of the present study. In the cultures from calf testes, the earliest viral antigen was proved 36 hours after the infection in the form of a finely granulated nuclear fluorescence with a yellow-green colour. The highest quantity of fluorescent cells was observed after 72 hours. A specific nuclear fluorescence was observed as early as on the sixth day after the infection in the nasal mucosa of experimentally infected calves. An adenoviral antigen was detected on the tenth day in 30% of the cells, and in separate fields of vision the number of fluorescent cells predominated over the negative ones. During the next days the intensity of the nuclear fluorescence diminished, whereas in the cells obtained by smearing on the eighteenth and twenty fourth days of the infection of calves, it was no longer observed. No adenoviral antigen was proved in the first preparations produced from spontaneously ill calves. Such was proved after a second taking of nasal and conjunctival samples six days later. A conclusion was drawn that the immunofluorescent direct method allows the identification of an adenoviral antigen in cells of the epithelium of the upper respiratory routes during the first days of calves infected with adenoviruses.