Immunochemical studies on sialic acid-containing lipopolysaccharides from enterobacterial species.

Lipopolysaccharides with sialic acid as a component were isolated from six bacterial serovars of the family Enterobacteriaceae. SDS-polyacrylamide gel electrophoresis, immunoblotting and passive haemagglutination demonstrated that epitopes are localized in the O-specific polysaccharide of lipopolysaccharides. The strains were tested for a serological relationship; the only distinct cross-reactivity recorded was between Escherichia coli serovars O24 and O56. The molecular mimicry phenomenon was found for Citrobacter freundii serovar O37 which shared epitopes with horse as well as human red blood cells.