Confirmation of the protective role of proteins from S. typhimurium in infection of mice with their natural pathogen.

The protective role of proteins from S. typhi-murium in infection of mice with their natural pathogens was confirmed. Hyperimmunization with either toxic or detoxified proteins, from the same batch, induced the synthesis of strongly precipitating antiprotein antibodies, and the mice were protected against infections with 15-75 LD100 of S. typhimurium. Reinfection of the same animals with 300-500 LD100 of S. typhi-murium induced, in the vaccinated mice, the synthesis of only anti-protein antibodies precipitating in agar-gel.