Enzyme-linked immunosorbent assay for Shiga toxin and Shiga-like toxin II using P1 glycoprotein from hydatid cysts.

Shiga toxin from Shigella dysenteriae type 1 strains and Shiga-like toxins (SLT) I and II from Escherichia coli bind to terminal alpha-D-Galp-(1----4)-D-Galp containing glycolipids. Hydatid cyst fluid isolated from sheep infected with Echinococcus granulosus contains a glycoprotein (P1gp) with a terminal alpha-D-Galp-(1----4)-D-Galp disaccharide. Preparations of P1gp were shown to interact directly with Shiga toxin and to inhibit the binding and cytotoxicity of Shiga toxin to HeLa cells. A sandwich ELISA was developed using preparations of P1gp as the toxin capture molecule, which, with an appropriate polyclonal antibody, was capable of detecting as little as 80 pg/well Shiga toxin and 132 pg/well SLT-II. Thus, the P1gp-toxin interaction forms the basis for a simple antigen-capture ELISA that may be useful clinically for the rapid detection and quantitation of Shiga and Shiga-like toxins.