Effect of synthetic disaccharide-protein conjugate as an immunogen in Salmonella infection in mice.

The synthetic disaccharide 3-O-alpha-tyvelopyranosyl-alpha-D-mannopyranoside, identical to the O antigen 9 determinant in Salmonella, covalently linked to bovine serum albumin and suspended in Freund complete adjuvant, was used as an immunogen in mice. Antibodies in high titer were formed against the O9 determinant as estimated by a bactericidal assay, whereas only low titers of hemagglutinating antibodies were found. A sensitive in vivo assay demonstrated that in immunized mice, after challenge with two strains of equal virulence but with different O antigens (O9, 12 and O4, 5, 12, respectively), the growth of the strain with the O9 determinant was suppressed in comparison to that with the O4 determinant.