Brucella Outer Membrane Lipoproteins Share Antigenic Determinants with Bacteria of the Family Rhizobiaceae

Abstract

ABSTRACT Brucellae have been reported to be phylogenetically related to bacteria of the family Rhizobiaceae . In the present study, we used a panel of monoclonal antibodies (MAbs) to Brucella outer membrane proteins (OMPs) to determine the presence of common OMP epitopes in some representative bacteria of this family, i.e., Ochrobactrum anthropi , Phyllobacterium rubiacearum , Rhizobium leguminosarum , and Agrobacterium tumefaciens , and also in bacteria reported to serologically cross-react with brucella, i.e., Yersinia enterocolitica O:9, Escherichia coli O:157, and Salmonella urbana . In particular, most MAbs to the Brucella outer membrane lipoproteins Omp10, Omp16, and Omp19 cross-reacted with O. anthropi and P. rubiacearum , which are actually the closest relatives of brucellae. Some of them also cross-reacted, but to a lower extent, with R. leguminosarum and A. tumefaciens . The putative Omp16 and Omp19 homologs in these bacteria showed the same apparent molecular masses as their Brucella counterparts. None of the antilipoprotein MAbs cross-reacted with Y. enterocolitica O:9, E. coli O:157, or S. urbana .