Abstract
Three aspects of the reported oral toxicity of Clostridium botulinum toxin, Type A, were investigated. No demonstrable migration of the crystalline toxin from the lumen of the intestine into the blood stream of the dog could be found. Evidence indicates that the crystalline toxin was inactivated by pepsin and chymotrypsin, but the toxin was found to be resistant to the action of trypsin. Comparison of the oral toxicity and the intraperitoneal toxicity of the crystalline toxin revealed that the product was not orally toxic. A spray-dried crude prepn. of the toxin demonstrated a low oral toxicity.