It has been shown that the toxic factors and the immunizing antigens in the cells
of C. pseudotuberculosis are distinct. These different antigens can be partially
separated by ammonium sulphate and acid precipitation and correspond to certain
precipitinogens. The antigens were also successfully separated by electrophoresis.
The dominating protective antigen is present in the S5O fraction and is represented
by the A line.
The toxic factor is present in the P50 and P50 a sup. fractions and corresponds
to the B₁ line. The P23 (X line) fraction is somewhat toxic and is slightly immunogenic.
The antigen present in the P30 a ppt. fraction gives rise to the B₂ line and is
neither protective nor toxic.