Seeds for delivery of edible vaccine

The oral delivery of plant-made vaccines is particularly attractive since the low costs, the heat stability, the avoidance of the injections and for the production of specific antibodies in the mucosa, where the major pathogens gain access to the body. In pig industry novel strategies are required to control enteric infections, in particular caused by verocytotoxic Escherichia coli (VTEC) strains and Salmonella thyphimurium, the two most important bacterial pathogens in the weaning period. The general aim of this study was to produce three different lines of transgenic tobacco plants expressing in the seeds the F18 fimbriae adhesive, the VT2e-B toxin (both from O138 VTEC strain) and the flgK flagellin (from Salmonella thyphimurium) respectively, as a model of edible vaccine. We also preliminary evaluated the immunogenic properties of transformed tobacco seeds in animal model. Tobacco leaf disks were transformed via Agrobacterium tumefaciens EHA105 with chimeric constructs containing structural parts of the major subunit FedA of the F18 adhesive fimbriae, VT2e B-subunit and flgK flagellin genes under control of a seed specific GLOB promoter: pBIpGLOB-F18, pBIpGLOB-VT2eB, pBIpGLOB-flgK. The GLOB promoter is the soybean basic 7S globulin promoter (DDBJ no. AX006477) and was used for the seed-specific protein expression. We showed that the foreign genes were stably accumulated and expressed in storage tissue by the immunostaining method. Obtained data showed the inheritance of transgenes in the R0, R1, R2 generations and the stable integration of VT2e-B, F18 and flgK genes into tobacco genome. Balb-C mice receiving transgenic tobacco seeds via the oral route showed a significant increase in IgA-positive plasma cell presence in tunica propria when compared to the control group with no observed adverse effects. Moreover oral administration of recombinant tobacco seeds expressing the antigenic proteins against VTEC strains can induce a protective effect against challenger strain in piglets.