Abstract: A method is disclosed for discriminating between cattle vaccinated against and those infected with Brucella spp. The method involves immunoassay using a purified polysaccharide containing 4,6-dideoxy-4-acylamido-D-mannopyranosyl units obtained from B. abortus or from cross-reacting organisms, and results in improved differentiation between vaccinated and infected animals. Test kits are also disclosed for performing the assay and a process is disclosed for obtaining the O-chain polysaccharides in high purity and yield.

Abstract: The antigenic O-chain polysaccharides from Brucella abortus and Yersinia enterocolitica serotype 0:9 have similar structure, i.e. 1-2 linked 4,6-dideoxy-4-formamido-.alpha.-D-mannopyranosyl units. The antigen is more readily isolated from the Yersinia and may be chemically modified to have a hydrophobic moiety attached thereto. The antigen can be adsorbed or coupled to carriers suitable for immunoassay use such as ELISA and RIA. A monoclonal antibody capable of specifically binding to B. abortus and Y. enterocolitica, has been produced. Assay procedures and kits therefor, are described.