Immunological characterization of protective antigens prepared by alkaline treatment of whole cells and from the culture filtrate of Erysipelothrix rhusiopathiae.

Culture filtrate and alkaline-extracted antigens from whole cells of an attenuated strain of Erysipelothrix rhusiopathiae (strain Koganei: serovar 1a) were fractionated with ammonium sulfate; both induced protective immunity in mice. Sephadex G-200 gel filtration revealed three protein fractions in the alkaline-extracted antigen and four protein fractions in the culture filtrate antigen. A fraction in the alkaline extract (NaOH P-2) and in the culture filtrate (CF P-2) induced protection in mice against challenge with a different serovar strain (strain Agata: serovar 5). Anti-NaOH P-2 and anti-CF P-2 mouse sera were protective against different serovars. Glycoprotein fraction derived from CF P-2 antigen by affinity chromatography with Con A-Sepharose 4B did not show protective activity. Western blotting between the antisera (anti-NaOH P-2, Anti-CF P-2 and anti-Koganei strain) and the antigens (NaOH P-2, and sonicated antigens of Agata, Fujisawa and Koganei strains) showed strong recognition of the same bands at 62, 42 and 41 kDa.