[Biological properties and chemical composition of a soluble fraction of Brucella abortus. Monospecific A or M antigens].

ABS, the supernatant of smooth B. abortus phenol-protected suspensions, is a protein, lipid, sugar and ARN complex containing all amino acids found in phenol-water fractions from B. abortus and B. melitensis. ABS is non-toxic and immunizes mice against B. abortus challenge. Chromium chloride easily binds ABS to sheep erythrocytes (E ABS) for a specific and accurate passive hemagglutination test in brucellosis. E ABS are agglutinated by all antisera to fractions of B. abortus or B. melitensis, but not by the monospecific anti M serum. A study of the antigenic relationships between ABS and phenol-water fractions from smooth brucella strains leads to the isolation of sub-fractions fron the phenol precipitates of B. abortus or of B. melitensis that could contain only A or M antigens which react only with their respective monospecific A or M serum.