Methods for the production and isolation of exfoliative toxin are described. Fermentation conditions were established under which large quantities of the crude material can be produced. Column chromatography methods, including carboxymethyl cellulose and hydroxyapatite, were utilized to purify the toxic protein. The pure toxin had a molecular weight of 26,000 as determined by polyacrylamide gel electrophoresis in sodium dodecyl sulfate. The pure toxin is a simple protein composed of 17 amino acids. Tests for carbohydrate and for alpha- and beta-hemolysin were negative. The mean effective dose of the purified toxin was 0.5 mug per newborn mouse.

A rapid solid-phase radioimmunoassay for staphylococcal enterotoxin A is described. The assay procedure requires 3 to 4 h for completion by using a competitive inhibition system in which the antibody is attached to bromacetyl cellulose particles. It is accurate to a level of 0.01 jg of enterotoxin A/ml in a variety of media such as ham, milk products, crab meat, custard, etc. No significant interference was found with any media or food product tested.

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Mouse thymocytes were used to compare mechanisms by which Vibrio cholerae and heat-labile Escherichia coli enterotoxins activate the adenylate cyclase-cyclic adenosine monophosphate (AMP) system. Both enterotoxins had their time-delayed increase in cyclic AMP neutralized by antisera to V. cholerae or E. coli enterotoxin, blocked by low concentrations of ganglioside GMI, and destroyed by prior heating. Enterotoxin activation of adenylate cyclase was

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