Precipitin Reactions with Soluble Antigens from Suspensions of Pasteurella Pestis or from Tissues of Animals Dead of Plague

The presence of water-soluble, heat-labile antigens in suspensions of Pasteurella pestis and in tissues of animals dead of plague has been confirmed. Antiserums from rabbits immunized against P. pestis or its products reacted in the precipitin test with soluble antigens from P. pseudotuberculosis and P. multocida. Absorption of these antiserums with heterologous antigens eliminates cross reactions. Specific reactions between soluble antigens from P. pestis and absorbed antiplague serums were obtained. Cross reactions occurring between antigens extracted from Bacterium tularense antiplague serums were noted. Precipitin tests performed with antigens obtained from tissues of animals dead of plague demonstrated the presence of soluble antigens in sufficient quantity to be of diagnostic value in tissues stored at 37 C for periods of at least 14 weeks.