Abstract
In trying to duplicate in vitro the conditions as they exist when botulinus toxin is taken by the mouth, we have observed that the acidity equal to that of the stomach contents not only leaves the toxicity of botulinus toxin undiminished, but would actually increase its potency. It has been repeatedly stated in the literature that botulinus toxin resists action of acids, but so far as we know nobody has observed the increase in potency of this toxin resulting from the change in its hydrogen ion concentration.
In attempting to establish the extent of this increase in potency we found that under the suitable conditions of the experiment the botulinus toxin which ordinarily kills mice in amounts not smaller than 3 × 10−7 cc. can be increased in potency to such an extent that 3 × 10−21 cc. occasionally and 3 × 10−18 cc. quite regularly kills mice of 18-20 grams in less than 48 hours after the intraperitoneal injection. While the total solids of such a minute dose of toxin amount to only 3 × 10−23 grams (this amount including also the inorganic portion of the medium) the toxic product thus obtained, nevertheless, possesses all the essential characteristics of bacterial toxins: it is thermolabile, it acts only after an incubation period, it reproduces in experimental animals typical symptoms of the botulinus poisoning and it exhibits strict specificity in its neutralization with the homologous antitoxin.
Our studies, thus far, were limited to the toxin produced by a single strain of Bacillus botulinus, but the experiments are in progress to determine whether the observation can be extended to toxins produced by other strains of Bacillus botulinus as well as to toxins of other bacteria.
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