No abstract

SUMMARYThe exotoxins produced by ten strains of C. ulcerans (two human, six bovine and two equine) have been studied. On the criteria oftoxin-antitoxin neutralisation and immunoprecipitation tests using highly specific diphtheria and C. ovis antitoxins with crude toxic filtrates, (NH4)2SO4 concentrates, and partially purified chromatographic preparations of these, together with the presence or absence of inhibition of the action of staphylococcal beta-haemolysin, and the reaction produced when injected intradermally into rabbits, two toxins could be identified, namely diphtheria toxin and C. ovis toxin. There was no evidence for the production of a third toxin specific for C. ulcerans. Five strains produced both diphtheria and C. ovis toxins. In four diphtheria toxin predominated, but in the fifth C. ovis toxin predominated. Two strains produced only diphtheria toxin and two only C. ovis toxin, though there was good but not complete evidence that a third strain (Revell) also fell into this latter group. Considerable variation occurred in the concentration of each toxin and, where both were present, in the proportion of each.

1. The toxin from Corynebacterium ovis, a phospholipase D (sphingomyelin phosphodiesterase D) that acts on 2-lysophosphatidylcholine and sphingomyelins, was purified by about 400-fold to homogeneity as judged by several criteria. [The EC number of the toxin (EC 3.1.4.41) has been allotted by the Nomenclature Committee of IUB, but has not yet been published.] 2. A new assay method performed in vitro, based on inhibition by the toxin of erythrocyte lysis by staphylococcal beta-haemolysin, was developed to facilitate the purification. 3. The toxin was found to be a basic (pI9.1) glycoprotein of mol.wt. 14,500 +/- 1,000. 4. The amino acid composition of the toxin was highly reminiscent of that of collagen, since it contained hydroxyproline, hydroxylysine and a high proportion of glycine, but preliminary tests showed no other similarities to collagen or proteins with similar compositions.