Characterization of biological activities of Brucella melitensis lipopolysaccharide.

Biological activities of lipopolysaccharide (LPS) from Brucella melitensis 16M were characterized in comparison with LPS from Escherichia coli O55. LPS extracted from B. melitensis was smooth type by electrophoretic analysis with silver staining. The endotoxin-specific Limulus activity of B. melitensis LPS was lower than that of E. coli LPS. There was no significant production of tumor necrosis factor-alpha and nitric oxide in RAW 264.7 macrophage cells stimulated with B. melitensis LPS, although E. coli LPS definitely induced their production. On the other hand, B. melitensis LPS exhibited a higher anti-complement activity than E. coli LPS. B. melitensis LPS as well as E. coli LPS exhibited a strong adjuvant action on antibody response to bovine serum. The characteristic biological activities of B. melitensis are discussed.