STUDIES ON BACILLUS TYPHOSUS TOXIC SUBSTANCES

Abstract

It was demonstrated that many multiples of minimal doses of Bacillus typhosus-resictmg factors can be neutralized by specific immune sera. The potency of a given serum can be conveniently titrated against increasing amounts of reacting factors. If the immune serum is diluted or if the amount of the reacting factors is too large for a given amount of serum, neutralization is obtained, but only irregularly. Normal and heterologous sera (therapeutic meningococcus and erysipelas horse sera), free of normal agglutinins or possessing normal agglutinins of low titer (1:16) for B. typhosus, are unable to neutralize the reacting factors. Questionable neutralization is obtained with a serum possessing normal Bacillus typhosus agglutinins in dilution 1: 64. The titer of the neutralizing antibodies increases in the course of immunization. Immune sera exercise a definite protection against the mortality induced by intravenous injection of B. typhosus culture filtrates.