An antigenic analysis ofPasteurella pestisby diffusion of antigens and antibodies in agar

Abstract

In addition to the envelope antigen, toxin and specific polysaccharide which are known to be produced byPasteurella pestis, evidence has been obtained for the presence of at least seven more antigens, some of which may be important in connexion with the pathogenicity of the organism. WhenP. pestisstrain 'Tjiwidej' was tested against its homologous antiserum by the agar diffusion precipitin technique of Ouchterlony, at least ten lines of precipitation formed between the antigen and antibody reservoirs. Evidence is presented to show that the majority of these lines, possibly all of them, represent different antigens. By using the diffusion precipitin technique in conjunction with animal experiments it has been possible to determine which lines of precipitation corresponded to antigens having some known physiological property. Thus one line of precipitation was found to represent the envelope antigen which protects mice from plague infection, another corresponded to the plague toxin and a third line to an antigen whose specificity is determined by a polysaccharide component. Some avirulent strains lack one or more of the antigens, one such strain which is neither protective for mice nor toxic produces only five of the ten lines which have been recognized. Maximum production of three antigens occurs when organisms are grown at 37° C, although the optimum growth temperature forP. pestisis 28° C. Cells grown at 20° C contain only traces of these three antigens, one of which is the protective antigen for the mouse.