Jan Holmgren1, Ivar Lönnroth1, Lars Svennerholm1
1Institute of Medical Microbiology and Department of Neurochemistry, University of Göteborg, Göteborg, Sweden
Tóm tắt
            By a double-diffusion precipitation-in-gel technique, isolated cholera toxin as well as its natural toxoid were shown to be fixed and precipitated by the ganglioside G
            M1
            but not by any of the related glycolipids G
            M3
            , G
            M2
            , G
            M1
            -GlcNAc, G
            D1a
            , G
            D1b
            , G
            T1
            , globoside, G
            A1
            , and tetrahexoside-GlcNAc. Twenty-five nanograms of G
            M1
            was enough to give a precipitation line with 1.2 μg of toxin, whereas about 50 ng was required with this amount of toxoid. G
            M1
            also inactivated the toxin in the ileal loop as well as in the intradermal models in rabbits. A 1: 1 molar ratio of ganglioside to toxin was found limiting, e.g., 100 pg of G
            M1
            could inactivate 5 ng (about 50 blueing doses) of isolated toxin. G
            M1
            inactivated crude toxin (culture fil rate) with the same efficiency as isolated toxin, and the inactivating capacity of G
            M1
            was unaffected by mixing with other gangliosides, indicating the specificity in the reaction between G
            M1
            and toxin. The other glycolipids tested did not inactivate toxin except G
            D1a
            and G
            A1
            which did so with approximately 1,000 times less efficiency than G
            M1
            . This identified the portion Gal → GalNAc [Formula: see text] as the critical region in G
            M1
            for toxin fixation, and it is postulated that this may be the tissue receptor structure for the cholera toxin.