Proteolytic Activity in Extracts of the Esophagus of Adults of Ancylostoma caninum and the Effect of Immune Serum on This Activity

Abstract

Physiological saline extracts of the esophagus dissected from adults of A. caninum showed proteolytic activity against casein. The pH otpimum of this activity was approximately 6. Since it has been postulated that enzymes necessary to the physiology of the worms serve as antigens and that antibodies to these enzymes inhibit their activity thereby making the environment of the host unsuitable for the worms, experiments were designed to test this hypothesis. When serum from a dog which had been infected periodically for 4 years with larvae of A. caninum and was refractory to further infection with A. caninum was added to the esophageal extracts before the addition of the substrate casein, this immune serum inhibited the proteolytic activity by as much as 88% when compared to preparations in which normal serum or saline were added to the extract.