The present study aimed to evaluate the immunogenic activity of three life attenuated strains of Salmonella Typhimurium isolated from guinea pig, by evaluating the excretion of faecal IgA in mice. The study was carried out with 28 four-week-old female mice of the Balb/c strain, distributed into four groups (seven mice per group): strain 1, strain 2, strain 3 and control group (PBS). Each mouse was inoculated with 109 CFU/100 µl of the attenuated strains using an orogastric probe. Fresh stool samples were collected at days 1, 9, 15 and 21 post-immunizations. The quantification of faecal IgA was carried out by an indirect in-house ELISA test. The results indicate that the mice inoculated with strains 1 and 2 presented a higher immunogenic activity (faecal IgA) compared to the Control group.

The aim of this study was to evaluate the protective capacity of an attenuated strain of Salmonella Typhimurium as a vaccine candidate against an experimental challenge. For this purpose, 51 recently weaned female guinea pigs from a commercial farm were used and distributed into three groups of 17 animals each: one group was inoculated with the attenuated strain and challenged, the second group was challenged only, and the third group served as a control (without attenuated strain and without challenge). The animals, according to their respective groups, were immunized after two weeks of adaptation to the new rearing conditions. Five weeks after immunization they were challenged with a virulent strain of S. Typhimurium. The health status was monitored for five weeks post-challenge and fecal samples were collected to demonstrate the excretion of IgA and S. Typhimurium. Additionally, necro...