[Trial of vaccination against Aujeszky's disease].

An experiment was carried out on pigs during which a passive immunity was created, similar to the colastral one, by injecting a specific for Aujeszky's disease gamma-globulin. After 48 hours the pigs were vaccinated with different quantities of living MK-25 vaccine and were checked for virus neutralizing antibodies against Aujeszky's disease. On the 90th and 180th days after the vaccination they were infected with a virulent virus (10(6) TCIU) and were checked clinically, serologically, virologically and pathomorphologically. It was proved that the pigs who had a passive immunity and were vaccinated with one dose of vaccine, did not build up a stable and active immunity after their vaccination, due to the neutralization of the vaccinal virus by passive immunity. The implementation of higher quantities of vaccine, however, overcame passive immunity and induced the build-up of active immunity after the vaccination.