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

Purified diphtheria toroid incorporated in egg yolk and mixed with a m edicinal plant seed was used to orally immunize rabbits against diphth eria infection. Animals were partially immunized against a lethal diph theria 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 apro tinin. Adult volunteers receiving protease inhibitor before administra tion of oral toroids have shown a significant rise in specific circula ting antitoxins.