Monoclonal antibody against O:5 Salmonella antigen cross-reacts with unidentified lipopolysaccharide epitope of Salmonella serogroup O:8 (C(2)-C(3)).

Monoclonal antibody (MAb) 8aC10 against Salmonella O:5 antigen was obtained after immunization of BALB/c mice with live attenuated mutant of Salmonella typhimurium. Antigen specificity of the MAb was characterized by ELISA, immunoblotting, passive hemagglutination (PHA), passive hemolysis and agglutination tests. In ELISA, PHA and immunoblotting the MAb reacted only with lipopolysaccharides (LPS) of Salmonella strains from group O:4 (B), expressing O:5 antigen. The MAb agglutinated in addition Salmonella strains with O:8 antigen from group C(2)-C(3) but did not react with purified LPS. These results demonstrate O:5 specificity of MAb 8aC10. Cross-agglutination with group C(2)-C(3) suggests the presence of similar but not identical epitope in O:8 expressing strains, which is possibly localized onto O-acetyl-abequose and abequose residues bound with a alpha-1-->3 linkage to the basic polysaccharide backbone of Salmonella LPS with O:5 and O:8 antigen respectively.