[Localization of viral antigen in cell cultures infected with the IBR-IPV virus].

Using the immunofluorescence method and fluorescein-isothiocyanate-labelled antibodies against the IBR-IPV virus the dynamics was followed up of the production of the viral antigen in primary cell cultures of calf kidney and a permanent cell line of calf kidney infected with IBR-IPV strains isolated in this country. To avoid nonspecific reactions in the fluorescence-and-serologic demonstration of the viral antigen a method was employed for the contrast staining with Evans blue. A positive reaction consisting in the specific fluorescence of the membrane enveloping the nucleus appeared at the earliest four hours after the infection of the cell cultures. No differences were found between the studied IBR-IPV virus strains so far as the place and time of appearance and the development of the viral antigen in the infected cell were concerned with the use of the two types of cell cultures.