The comparative characteristics of preparations of Yersinia pestis capsular antigen F1 obtained from producer strains with different lipopolysaccharide structures

: The main protective antigen of the causative agent of plague is capsular antigen F1. The preparations of this antigen isolated from Y.pestis strain EV are characterized by a high content of polysaccharide chains of endotoxins. This can be avoided by using R-variants of bacteria as producers. In this work the comparative study of the preparations of antigen F1 obtained from Y.pestis strain EV, Escherichia coli producer strain HB101 pFS1 with the complete structure of LPS and Salmonella minnesota producer strain Re595 pFS1 with maximally reduced LPS has been made. As revealed in this study, the physico-chemical properties of these preparations (the isoelectric point, electrophoretic mobility, the molecular weight of subunits) are identical. The preparation of antigen F1 obtained from S.minnesota has been found to give the highest yield and to have the lowest content of polysaccharide admixtures. This preparation has proved to possess the maximal protective potency, which may be linked with the adjuvant and immunogenic activity of microadmixtures of glycolipid Re, contained in F1.