[Immunogenic properties of S. choleraesuis for pigs].

The aim of this work was to determine pathogenic properties for white mice of 3 S. choleraesuis strains. Two of these strains (No. 6 and Ivanovice) were attenuated, and the third strain (No. 964) was isolated from a pig which died of salmonellosis. Pathogenic properties and shedder state of the attenuated strains were tested in pigs with special reference to the persistence of the shedder state in the lymph nodes and internal organs of pigs after their vaccination and subsequent challenge. Specific agglutinin level in pigs before and after administration of the attenuated S. choleraesuis strains was also determined. During the investigations the method for industrial production of the lyophylized vaccine was worked out. The vaccine, containing the attenuated Ivanovice strain, proved to be harmless for pigs, under laboratory conditions, and it protected pigs against experimental challenge 3 weeks after their vaccination. After this time no salmonellae were found in the lymph nodes and internal organs of pigs. No salmonellae were also detected in faeces of these pigs during 10 days after their vaccination. In pigs vaccinated and challenged 3 weeks later no salmonellae were found in the lymph nodes and internal organs, 3 weeks after the challenge, although these micro-organisms were detected in faeces of these pigs 2 to 5 days after challenge. The only exception was one pig; from its lymph node salmonellae were isolated. The three above-mentioned S. choleraesuis strains proved to be pathogenic for white mice.