NEW ANTIGENIC COMPONENT OFPASTEURELLA PESTISFORMED UNDER SPECIFIED CONDITIONS OF pH AND TEMPERATURE

Abstract

An antigenic surface component has been found to be formed in vitro by Pasteurella pestis incubated in casamino salt xylose medium at pH values of 5.0-6.7 at temperature 35[degree]C-41[degree]C. The formation of this component was associated with a change in the electric charge of the cells as expressed by decrease in their electrophoretic mobility. The formation of this antigen called "pH 6 antigen" was common to all the P. pestis strains tested, virulent as well as non-virulent. The non-identity of this antigen with the other known surface antigens of P. pestis was established and its stability to different physical and chemical treatment has been studied. The pH 6 antigen was found to be invariably formed in vivo in rabbits and mice inoculated with cells devoid of this antigen when they propagated in vitro. The possible relation of this antigen to pathogenesis of plague was supported by the data indicating increase of mortality in groups of mice inoculated with virulent cells which contained the pH 6 antigen.