Summary
A crude protein fraction (FIB) and a toxin were prepared from Pasteurella pestis grown in casein hydrolyzate mineral carbohydrate medium, by fractionating the culture filtrate with (NH4)2SO4. The protein nitrogen, sulfur, phosphorus and the ultraviolet light absorption values were similar to those published by other investigators. Electrophoresis, however, revealed two rather than one component. Both the FIB and the toxin were antigenic.
One inoculation of either protein 1/2 hr before subcutaneous infection with virulent organisms induced immediate protection against P. pestis but not against Pseudomonas pseudomallei or Pasteurella tularensis. The degree of protection induced by one inoculation of FIB increased as the interval between treatment and infection increased.
The immediate protection against P. pestis, induced by the proteins, was probably specific but the participation of nonspecific factors was not precluded.
Footnotes
This work was sponsored by the Office of Naval Research and the Bureau of Medicine and Surgery, U. S. Navy, under the terms of a contract between the Office of Naval Research and the Regents of the University of California. Reproduction in whole or in part is permitted for any purposes of the United States Government.
