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.
