[Participation of Aujeszky's disease virus in the respiratory diseases of swine].

Clinical, virologic and seroligic investigations on vaccinated and unvaccinated pigs fattened on two farms with a record of a stationary Aujeszky's disease infection were carried out. Aujeszky's virus was isolated from the lungs of all pigs and partially of other viscera of some of the animals. The serologic studies revealed the dynamics of the antibody titer reise which spoke of the development of an infectious process. The clinical signs observed along with the morphologic changes characteristic of pneumonia, coupled with the advancement of the Aujeszky's disease infection demonstrated that on stationary fattening pig farms Aujeszky's disease assumed the course of a respiratory affection. The discripancy between the results obtained with vaccinated and unvaccinated animals, which were negligible on one of the farms and considerable on the other, was due to variations in the intensity of the infection as well as to the level of passive immunity.