Synthetic disaccharide-protein antigens for production of specific 04 and 09 antisera for immunofluorescence diagnosis of salmonella.

The synthetic disaccharides abequose 1 leads to a 3 mannose and tyvelose 1 leads to a 3 mannose, representative of Salmonella O-antigen 4 and 9 respectively, were covalently linked to bovine serum albumin (BSA) . Antisera from rabbits immunized with these immunogens were used in indirect immunofluorescence assay for the identification of group B (O-antigen 4) and D (O-antigen 9) Salmonella. A total of 1030 enteric bacterial strains were tested, including 207 group B and 55 group D Salmonella. The anti-abequose-mannose-BSA serum correctly identified all Salmonella group B strains tested. The anti-tyvelose-mannose-BSA serum correctly indentified all Salmonella group D bacteria examined with the exception of 11 of 18 Vi-positive S. typhi strains which did not not stain until the Vi-antigen was removed by boiling. Among the 768 strains representing Salmonella other than groups B and D, E. coli, Shigella, Citrobacter, Klebsiella, Enterobacter, Serratia, Proteus, Vibrio, Pseudomonas, Aeromonas, Yersinia, Bacteroides and Fusobacterium only 5 positive reactions were found. These were observed with Y. pseudotuberculosis strains which have the same disaccharide antigenic determinants as Salmonella O-antigen 4 and 9 respectively. The high specificity of the antisera elicited by the synthetic disaccharide-BSA immunogens make them suitable for a specific and rapid identification of Salmonella bacteria belonging to serogroups B and D.