Properties of an immunogenic fraction from Brucella abortus 45/20.

Hot saline extracts of Brucella abortus strain 45/20 contain up to 4 protein components. Some of these components are shared with other Brucella strains but one appears specific to B. abortus 45/20 or possibly other non-smooth Brucella strains. The extracts are antigenic in guinea-pigs and evoke protective immunity against virulent B. abortus. The rough antigen specific activity appears to be associated with a protein component rather than lipopolysaccharide.