[Investigations on live vaccine against pig salmonellosis]

The purpose of the work was to determine pathogenic properties for guinea-pigs of of S. choleraesuis-Ivanovice (the attenuated strain used for the production of live vaccine) and S. choleraesuis no. 964 (the virulent strain used for infection of pigs under experimental conditions). The effectiveness and safety of the live vaccine prepared from the Ivanovice strain was also tested in pigs under laboratory and field conditions. The results of the experiments showed that both strains can be differentiated by subcutaneous, intramuscular and intraperitoneal inoculations of guinea-pigs. This finding is especially important for the routine state control of the vaccine, containing the Ivanovice strain. Field and laboratory experiments showed that the vaccine is effective and safe for pigs kept in fattening centres. Salmonellae contained in the vaccine were not excreted in faeces of vaccinated pigs. The serum agglutination titre ranged from 256 to 1024, 14 days after vaccination. No salmonellae were found in internal organs, lymph nodes and bone marrow 1-6 months after vaccination. The vaccinated pigs were fully protected against infection with the virulent S. choleraesuis strain under laboratory conditions. The immunity lasted 4 months. Most vaccinated pigs shed salomonellae in faeces for 10 days after infection, but later no shedding was observed. No salmonellae were isolated from internal organs of immunized pigs 2 months after infection, except in 1 out of 12 pigs tested, in which salmonellae were found in the caecum.