Serological and structural relationships between Escherichia coli O: 98 and Yersinia enterocolitica O: 11,23 and O: 11,24 lipopolysaccharide O-antigens

The serologically related lipopolysaccharide O-antigens of Yersinia enterocolitica serotypes 11,23 and 11,24 and of Escherichia coli O: 98 were analysed by composition analysis, methylation, and the use of one- and two-dimensional nuclear magnetic reasonance methods. They were found to be composed of the same basic linear unbranched polysaccharide of repeating tetrasaccharide units containing 2-acetamido-2-deoxy-D-glucose (D-GlcNAc), 2-acetamido-2-deoxy-D-galacturonic acid (D-GalNAcA), and 2-acetamido-2,6-dideoxy-L-glucose (L-quinovosamine, L-QuiNAc), having the structure[Formula: see text]The lipopolysaccharide O-antigens of E. coli O: 98 and Y. enterocolitica O: 11,24 were polymers of the above repeating unit, whereas that of Y. enterocolitica O: 11,23 was a linear polymer of the same repeating units in which the α-D-GalpNAcA residues were stoichiometrically substituted by acetyl groups at O-3.Key words: lipopolysaccharide, polysaccharide, Escherichia coli, antigen, nuclear magnetic resonance.

Structure of the lipopolysaccharide O-antigen of Pseudomonas cepacia serotype A

The O-antigenic polysaccharides of the lipopolysaccharides produced by three isolates of Pseudomonas cepacia serogroup A were analysed by composition, methylation, periodate oxidation, and two-dimensional nuclear magnetic resonance methods. They were found to be identical linear unbranched polymers of a repeating trisaccharide unit containing 2-acetamido-2-deoxy-D-galactose and L-rhamnose residues (2:1) and have the structure[Formula: see text]Key words: lipopolysaccharide, Pseudomonas cepacia, O-antigen.

Protection against Klebsiella pneumoniae induced lobar pneumonia in rats with lipopolysaccharide and related antigens

The immunoprotective role of lipopolysaccharide and related antigens from Klebsiella pneumoniae was studied in a lobar pneumonia model developed in rats. Various antigens were obtained by different chemical treatments of the lipopolysaccharide. All these antigens (purified lipopolysaccharide, reduced lipopolysaccharide, lipopolysaccharide – bovine serum albumin complex, and lipid A – bovine serum albumin complex were tested for pyrogenicity and the Shwartzman reaction. The lipopolysaccharide and the various related antigens were pyrogenic and elicited a positive Shwartzman reaction at high concentrations. However, at low concentrations, the same preparations did not show any side effects. All these antigens, on the other hand, were protective against bacterial challenge in Klebsiella pneumoniae induced lobar pneumonia in rats, as the bacterial colonization of lungs in the immunized animals was significantly lower when compared with the controls. The alveolar macrophages from these animals also showed significantly more uptake of Klebsiella pneumoniae as compared with those obtained from control animals. Key words: lipopolysaccharide, vaccine, pneumonia, protection.