Cross‐reactivity between the mannan of Candida species, Klebsiella K24 polysaccharide and Salmonella C₁ and E O‐antigens is mediated by a terminal non‐reducing β‐mannosyl residue

Abstract

Rat monoclonal antibody MASCl-MR9 (MR9) binds to a mannan of Candida species and the 0-antigenic polysaccharides of Salmonella bacteria of serogroups C, (CO) and E (EO). Saccharides (3 -10 residues) of mammalian origin with terminal and internal Manpa-1-2, Manpa-1+3 and Manpa-1-6 residues also failed to inhibit at any concentration. None of the saccharides with internal P-mannosyl residue was able to inhibit the MR9 antibody. Monosaccharides D-mannose, P-D-Manp-1 -0Me and 1 3 anhydro-D-mannitol inhibited the MR9 monoclonal antibody whereas a-D-Manp-1 -OMe, P-D-Glcp-1 -OMe, and 8-D-Galp-1-OMe did not. In addition a Klebsiella K24 capsular polysaccharide containing a P-~-Manp(l+4)-a-~-GIcA (GlcA, glucuronic acid) as a structural element possessed an inhibitory activity. MR9 therefore recognizes an epitope within p-mannose monosaccharide residues at the terminal non-reducing ends of carbohydrate chains in mannan, and polysaccharides in Salmonella serogroups CO and EO and Klebsiella K24.Protein carbohydrate interactions are involved in many biological processes such as the binding of antibodies to their epitopes and attachment of bacteria, viruses and hormones to their receptors (Lentz, 1990;Quiocho, 1986). The molecular mechanisms for recognition in these interactions in many instances still remain to be fully delineated. Immunochemical specificity is one aspect of molecular recognition which currently commands high interest. The composition of epitopes in biological molecules and the factors that govern their recognition by antibody are complex and poorly understood. This complexity is especially true for carbohydrates where sequence as well as linkage are involved in the determination of immunochemical specificity.Our laboratory has been involved in the use of monoclonal antibodies for definition of structure/function relationships and identification of the structural bases for molecular recognition , Luk et al., 1991, Nnalue et al., 1992 Abbreviations. I,,,, the concentration of an inhibitor necessary to lower the antibody titer with 50% relative to controls with no inhibitor added; Kdo, 3-deoxy-~-manno-octu~osonic acid; Rha, rhamnose; GlcA, glucuronic acid. microbial antigens are well-suited for the investigation of epitopes. It is at present not clear whether all epitopes recognized by a single molecular species of antibody are identical or, at least, similar and whether all antigens which crossreact share identical epitopes. A cross-reactivity between the mannan of Candida species and the 0 antigen i.e. polysaccharide of Salmonella serogroup C, using a rabbit polyclonal antiserum elicited with a synthetic trisaccharide-BSA conjugate has been described (Ekwall et al., 1982). We have confirmed this finding when we isolated a rat monoclonal antibody, MASCl-MR9 (MR9), which not only reacted with both these antigens but also with the 0 antigen of Sulmonella species serogroup E (Nnalue et al., 1991 j. The mannans of Candida species are highly complex branched molecules comprising mainly mannose in various linkages....

Immunochemical characterization of O polysaccharides composing the alpha-D-rhamnose backbone of lipopolysaccharide of Pseudomonas syringae and classification of bacteria into serogroups O1 and O2 with monoclonal antibodies

“…These observations are consistent with suggestions made previously (6,13,22,27,28,31,38,46) based on the results of the immunochemical investigation of polysaccharides from other species of bacteria. It is, however, obvious that to precisely determine the epitopes recognized by our MAbs, moredetailed analyses, especially competition ELISAs with monosaccharides and synthetic oligosaccharides with different compositions and lengths as competing antigens have to be carried out.…”

Monoclonal antibody against O:5Salmonellaantigen cross-reacts with unidentified lipopolysaccharide epitope ofSalmonellaserogroup O:8 (C2–C3)

“…Studies with MAbs have found new unknown LPS epitopes, in the O‐antigens of different Salmonella as well as in non‐closely related microorganisms [26,27]. In other our investigations MAbs directed against O:3 Salmonella antigen reacted also with LPS antigens of other Salmonella serogroups and E. coli O:75 [28], and Candida albicans (unpublished data).…”

Structural and immunochemical characterization of β-1,2-linked mannobiosyl phosphate residue in the cell wall mannan of Candida glabrata

“…The Salmonella C 1 O-polysaccharide has a considerable amount of β-1,2-linked mannose residue, which was also observed in Candida mannans (Shibata et al 1985;Lindberg et al 1988). Subsequently, Nnalue et al (1994) have demonstrated that the antigenic similarity between these species is carried by a nonreducing terminal β-mannose residue. Aksoycan et al (1988) have described serologic cross-reactivity between C. glabrata mannan and Escherichia coli (O75 or O163) O-antigen.…”