Protective activity and antigenic analysis of fractions of culture filtrates of Erysipelothrix rhusiopathiae.

The protective activity in mice and antigenic composition of the culture filtrate of 11 strains of Erysipelothrix rhusiopathiae were compared. Protective activity was found in the first (P-1) fraction obtained by Sephadex G-200 gel filtration of the culture filtrate of each strain. Comparing the 50% protective dose (PD50) of the P-1 fraction of the 11 strains by active immunization, highly protective activity was shown by 5 strains, such as Agata, Fujisawa, Shizuoka-63, Koganei 65-0.15 and SE-9. For the 50% effective dose (ED50) determined by passive protective studies, the four strains, Agata, Fujisawa, Koganei 65-0.15 and SE-9 were shown to be highly protective. However, strains 2179 and 2553 showed low activities in both PD50 and ED50. The highly and weakly protective strains were compared by western blot analysis for the protein components. In most strains tested, there were two protein bands of molecular weight of 64 kDa and 43 kDa. Therefore, these two structural proteins were common to the strains and were associated with stimulation of a protective effect in mice.