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Injection of Clostridium welchii (C. perfringens) type D epsilon toxin into sheep caused large increases in catecholamine and cyclic adenosine 3',5'-monophosphate levels and moderate increases in cyclic guanosine 3',5'-monophosphate levels. Haemoconcentration also occurred. It is suggested that a rapidly developing brain oedema is the stimulus for a release of catecholamines which in turn activates adenyl cyclase. The resulting rise in cAMP causes glycogenolysis and hyperglycaemia.

Heat-stable enterotoxins from a bovine and porcine strain of Escherichia coli were isolated and showed significant differences in amino acid composition and heat stability.

Antibodies against epsilon toxin were isolated from hyperimmune horse serum by affinity chromatography. Purified epsilon prototoxin covalently bound to Affigel 202 was used as immunosorbent, and antibodies were eluted with 6.0 M guanidine chloride. In a single run 80 mg of antibody could be recovered from a 20 microliter column of immunosorbent. The antibody was shown to belong to the IgG(T) class of immunoglobulins.

Heat-stable enterotoxins (ST-124 and ST-1261) have been isolated from two different enterotoxigenic Escherichia coli of bovine (124) and porcine (1261) origin. The enterotoxin preparations were isolated by ultrafiltration and ion-exchange chromatography and were both active in the suckling mouse test and pig ligated loop test in the nanogram range. The bovine (ST-124) enterotoxin was not stable to heating in its isolated form, and significant differences in amino acid composition were observed between the two enterotoxins. Although both toxins were active at similar levels in the suckling mouse and pig ligated loop tests, ST-124 lacked the ability to cause the profound secretory responses seen with ST-1261 in the weanling pig ligated loop.

Enzymatic activation of Clostridium perfringens epsilon prototoxin removed a small basic part of the molecule, causing a slight change in molecular weight (32,700 to 31,200) and a large change in isoelectric point (from pH 8.02 into fractions of 5.36 and 5.74).