Clostridium difficile is the most frequently identified cause of antibiotic- associated diarrhea and colitis. The overall goal of this project is to develop specific plant-derived secretory IgA (SIgA) antibodies to neutralize toxins A and B of this pathogen. This approach will provide a novel and inexpensive means to prevent and/or treat Clostridium difficile diarrhea. This project is made possible by our recent identification from a human phage antibody library of a large number of toxin A and B specific Fabs. In phase I these Fabs will be moved into plant expression vectors and used to prepare transgenic plants producing toxin NB specific SIgAs. These antibodies will be purified and tested for functional activity. In phase II, complete IgA plantibodies will be purified tested in suitable animal models in preparation for human clinical trials. This approach will provide a novel and inexpensive means to make and deliver antibodies to prevent or treat this important human pathogen. PROPOSED COMMERCIAL APPLICATIONS: Secretory IgA anti-Clostridium difficile plantibodies will provide a novel therapeutic for treatment of this severe diarrheal disease.