[Comparative analysis of antigens from different Brucella species using immunoblotting with antisera from immunized...

Brucella antigens recognized by IgG antibodies in cell lysates from various Brucella species differing by the origin, biological, and virulent properties (including the reference, vaccine, and newly isolated strains) were compared by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Proteins in SDS-cell lysates were separated by 12% SDS-PAGE and protein gels were stained with Coomassie brilliant blue R-250 and Silver reagent. SDS-PAGE showed differences in the protein profiles of 15 strains of different species. Immunoblotting revealed that rabbit S-antisera contained IgG reacting with S-LPS and identical proteins of 90 to 16 kDa belonging to B, melitensis, B. suis, B. abortus, and B. neotomae strains. B. canis strains had 4 antigens reacting with these antisera, whereas B. ovis had none. No agglutinating antibody were detected by the standard tube agglutination test with smooth Brucella strains in rabbit R-antisera. By contrast, immunoblotting analysis with these sera demonstrated common 90-16 kDa antigens in the strains of B. melitensis, B. suis, B. abortus, B. neotomae, and B. canis. B. ovis possessed none of these antigens. These results confirm that all Brucella species except B. ovis possess common protein antigens reacting with IgG.