Heterologous protections in experimental salmonellosis.

Immunizations of mice with proteins from S. paratyphi B protected the animals against infection with a concentration of S. paratyphi C which killed the controls and against an infection with 50 LD100 of the homologous S. paratyphi B. The sera of the infected mice showed common precipitation lines of proteins from the two species belonging to different serogroups. Consecutive inoculations with S. typhimurium of both groups of vaccinated mice protected the animals against the infection with their natural pathogen. Immunizations with proteins from S. cholerae-suis protected about 70% of the mice infected with S. paratyphi B and with S. paratyphi C; a higher protection was not, however, induced against infection with the homologous strain. Consecutive infections with S. typhi-murium of the mice resulted in total protection of the animals previously inoculated with S. paratyphi B and S. paratyphi C; the group of mice infected with S. cholerae-suis was less protected against the subsequent inoculation with S. typhi-murium (about 50%). In the infections of mice, S. paratyphi B and S. paratyphi C, seem related to S. typhi-murium by common proteins; the proportion of common protective determinants is not yet known.