Immunochemistry of Salmonella O-antigens: preparation of an octasaccharide-bovine serum albumin immunogen representative of Salmonella serogroup B O-antigen and characterization of the antibody response.
The O-antigenic polysaccharide of phenol-water extracted Salmonella typhimurium (O antigens 4, 12) lipopolysaccharide was enzymatically cleaved by phage P22 endorhamnosidase. An octasaccharide with the (formula: see text) structure Gal-Man-Rha-Gal-Man-Rha was isolated and shown to retain the O-antigen 4 specificity of the native polysaccharide. After oxidation of the terminal reducing rhamnose residue to the corresponding aldonic acid, the octasaccharide was covalently linked to bovine serum albumin (OLS-BSA) by use of a water-soluble carbodimide. The resulting conjugate showed O-antigen 4 specificity in enzyme-linked immunosorbent assay (ELISA) ans passive hemagglutination inhibition tests. Immunization of rabbits with the OLS-BSA conjugate gave rise to antibodies directed toward both the octasaccharide and the carrier protein. ELISA titration with synthetic disaccharide-protein conjugates as antigens revealed that the antibody titer against the mannose-rhamnose structure was higher than against the abequose-mannose structure. In rabbits immunized with heat-killed whole bacteria the titers against the two disaccharides were equal. The reason for this difference is not obvious. It is evident, however, that the OLS-BSA conjugate elicited in rabbits O-antibodies with the same specificity as whole bacteria.
D000818:Animals; D000942:Antigens, Bacterial / Q000096:biosynthesis; D001435:Bacteriophages / Q000201:enzymology; D055598:Chemical Phenomena; D002621:Chemistry; D002642:Chick Embryo; D007114:Immunization; D011135:Polysaccharides, Bacterial / Q000276:immunology* / Q000378:metabolism; D011817:Rabbits; D012477:Salmonella enteritidis / Q000276:immunology*; D012486:Salmonella typhimurium / Q000276:immunology*; D012710:Serum Albumin, Bovine / Q000276:immunology* / Q000378:metabolism
D000942:Antigens, Bacterial; D011135:Polysaccharides, Bacterial; D012710:Serum Albumin, Bovine