Structural characterization of the O-polysaccharide of the lipopolysaccharide produced by Salmonella milwaukee O:43 (group U) which possesses human blood group B activity.

The O-polysaccharide of the lipopolysaccharide produced by Salmonella milwaukee O:43 (group U) was shown by composition analysis, methylation, periodate oxidation, and 1H and 13C nuclear magnetic resonance spectroscopic analytical methods to be a polymer of branched pentasaccharide repeating units having the structure: [formula: see text] The blood-group activity of the O-polysaccharide was established by its serological reactivity with a specific monoclonal antibody to human blood group B, using passive hemagglutination and ELISA assays, indicating the common antigenic epitope to be a nonreducing terminal trisaccharide unit composed of L-Fucp and D-Galp (1:2) residues.