An antigenic basis for virulence in strains of Salmonella typhimurium

A study has been made of the antigenic relationships between a virulent and an avirulent strain of Salmonella typhimurium. Evidence is presented which supports the hypothesis that the susceptibility of the mouse to infection by S. typhimurium is due to an antigenic relationship between host and parasite. The antigen shared between host and parasite, appears to be absent or is masked in the avirulent strain.