Differentiation of Helicobacter pylori isolates based on lectin binding of cell extracts in an agglutination assay

Plant and animal lectins with various carbohydrate specificities were used to type 35 Irish clinical isolates of Helicobacter pylori and the type strain NCTC 11637 in a microtiter plate assay. Initially, a panel of eight lectins with the indicated primary specificities were used: Anguilla anguilla (AAA), Lotus tetragonolobus (Lotus A), and Ulex europaeus I (UEA I), specific for alpha-L-fucose; Solanum tuberosum (STA) and Triticum vulgaris (WGA), specific for beta-N-acetylglucosamine; Glycine max (SBA), specific for beta-N-acetylgalactosamine; Erythrina cristagali (ECA), specific for beta-galactose and beta-N-acetylgalactosamine; and Lens culinaris (LCA), specific for alpha-mannose and alpha-glucose. Three of the lectins (SBA, STA, and LCA) were not useful in aiding in strain discrimination. An optimized panel of five lectins (AAA, ECA, Lotus A, UEA I, and WGA) grouped all 36 strains tested into eight lectin reaction patterns. For optimal typing, pretreatment by washing bacteria with a low-pH buffer to allow protein release, followed by proteolytic degradation to eliminate autoagglutination, was used. Lectin types of treated samples were stable and reproducible. No strain proved to be untypeable by this system. Electrophoretic and immunoblotting analyses of lipopolysaccharides (LPSs) indicated that the lectins interact primarily, but not solely, with the O side chain of H. pylori LPS.