Vaccines that stimulate mucosal immune responses of the gastrointestinal tract would be advantageous since such formulations would provide immunity at the site of pathogen entry. Edible vaccines have received much attention since, in theory, they represent a source of vaccine that would stimulate immune responses of the gastrointestinal tract, be cost-effective to produce, safe to administer, and a highly stable form for shipment throughout the world. Unfortunately, there are many practical problems that remain when trying to reduce such potential into reality. Studies to be conducted here will directly address some of the most important challenges that face this technology for developing edible subunit vaccines in soybeans which could be applied to the formulation of novel human gastrointestinal vaccines. We propose the use of a model antigen, E. coli FanC, so that definitive questions can be addressed regarding the protective nature of the humoral and cell mediated gastrointestinal response induced when this edible vaccine is coupled with an oral adjuvant. Expression of the model antigen, E. coli FanC, in transgenic soybeans will be used to provide practical information regarding the utility of edible subunit vaccines. Following oral immunization with FanC expressed in transgenic soybeans coupled with an oral adjuvant, the humoral and cellular immune response will be defined at mucosal and systemic sites. In addition, the ability of this vaccine formulation to protect mice against a challenge with enterotoxigenic E. coli will also be determined. Finally, novel formulations of this edible vaccine will be investigated for their potential to stimulate gastrointestinal immunity. Despite the promise of plant based vaccines as a low cost method for stimulating gastrointestinal immunity, significant questions still remain about the feasibility of developing such methods for immunizing humans. The present proposal focuses on the practicality of using edible subunit vaccines for oral immunization.