The uterotropic strains SH6 and O1 were studied immunoelectrophoretically to establish their antigenic relationship. The more readily diffusing component of the O-antigenic fraction of the strains proved immunologically identical with LPA  of the R Brucella organisms, while the slower component showed common determinants with the O-antigenic fraction of Yersinia pseudotuberculosis. Immunodiffusion revealed that the O-antigenic fraction of the O1 strain and LPA of the S Brucella organisms contained common antigenic determinants having a weak immunologic activity, and this could explain the agglutination reaction after Wright and Huddleson of the sera from cows with infections caused by the uterotropic strains described. It was established through electrophoresis that in contrast to Yersinia enterocolitica 373 the O-antigenic fraction of the uterotropic strains is immunologically identical with LPA of the R Brucellae. An analogy is shown to exist between the immunologic activity of cow sera from infected animals and the A substance as well as at higher agglutination titers after wright of substance B as described by Amarasinghe.
Abortion, Veterinary Animals