[Aspects related to the antigenic structure and serological specificity of brucellae phylogenetically related to S-...

The antigenic structures and serological properties of Brucellae S- and R-forms, phylogenetically differentiated, and dissociated R-variants are studied by means of gel-precipitation, immunoelectrophoresis and fixation of the complement. The Brucella suis 1330S, Brucella suis 1330R, Brucella ovis 02 and Brucella abortus 99 are involved in the experiments. Both specific and general antigenic structures are established in all strains studied, but only homologous antibodies from the antigen-antibody complex in the complement-fixation test, induced by the phylogenetically differentiated S- and R-forms (Brucella ovis) or brucellae, diverged into R-variants. Cross complement-fixation tests between the antisera, prepared against S-forms and antigens from natural R-forms (Brucella ovis) or dissociative R-forms (R-variants) have not been observed. Also cross reactions between antisera, induced by R-forms (natural R-forms--Brucella ovis, or dissociative R-variants) and antigens, obtained from S-forms of brucellae are found.