ORAL IMMUNIZATION AGAINST DIPHTHERIA AND TETANUS INFECTIONS BY FLUID DIPHTHERIA AND TETANUS TOXOIDS

Purified diphtheria toroid incorporated in egg yolk and mixed with a medicinal plant seed was used to orally immunize rabbits against diphtheria infection. Animals were partially immunized against a lethal diphtheria toxin challenge. The immunity was complete when gastric enzyme juices were inhibited before oral vaccination by aprotinin, a natural protease inhibitor. Rabbits and monkeys were orally immunized against both diphtheria and tetanus in the same way by pre-treatment with aprotinin. Adult volunteers receiving protease inhibitor before administration of oral toroids have shown a significant rise in specific circulating antitoxins.