Coupling of acid labile Salmonella specific oligosaccharides to macromolecular carriers

A coupling method for covalent attachment of acid labile oligosaccharides isolated from S. typhimurium O-polysaccharide to macromolecular carriers is described. Arylamine groups were introduced into the terminal reducing end of oligosaccharides by reacting them with 2-(4-aminophenyl)-ethylamine. After subsequent conversion to the corresponding saccharide-phenylisothiocyanato derivatives saccharides were covalently linked to free epsilon-lysylamine groups of different carrier proteins. The resulting conjugates were highly immunogenic and elicited in rabbits both anti-harptenic and anti-carrier protein specific antibodies. Some of the advantages of this coupling procedure are: (i) it can be used with oligosaccharides containing highly acid or alkali labile structures and/or glycosidic linkages, (ii) it produces conjugates with high degrees of substitution at low saccharide/protein molar input ratios, (iii) it does not grossly affect the immunogenic specificities of the carrier protein, and (iv) it is suitable for preparation of highly substituted affinity columns, e.g., coupling to a polyacrylamide matrix.