Our experiences with isolation of heat-labile enterotoxin from Escherichia coli

From the Escherichia coli strain isolated from a patient suffering from diarrhoea a homogenate and concentrated culture filtrate were prepared. From these materials the heat-labile enterotoxin was isolated after its elution with 0.2 M D-galactose from Sepharose 6B column. The obtained enterotoxin was positive in the rabbit ileal loop test up to a concentration of 1 microgram protein/ml. In the immunodiffusion test it reacted in a concentration up to 5 micrograms protein/ml with anticholeragen and in a concentration up to 30 micrograms protein/ml with its specific antiserum. This antiserum was prepared by intramuscular immunization of rabbits by enterotoxin with complete Freund's adjuvant.