Evaluation of gastric degradability of antigenic protein espresse in tobacco seeds

Plants have been recognized as expression system for the production of edible vaccine because of the possibility of introducing antigenic proteins into their genoma. In livestock, transformed plants for the expression of immunogenic proteins, could be administered, orally, in feed to induce mucosal immune response in the gastrointestinal tract. Moreover edible vaccines for veterinary use could reduce costs of traditional vaccines associated with the production, the cold storage, and parenteral administration. However the most important problem related to the oral delivery route is the potential for antigen degradation in the gastrointestinal tract. For these reasons the aim of this study was the evaluation of the effect of swine gastric fluid on VT2e-B antigenic protein, derived from a strain of Oedema disease E. coli, expressed in tobacco seeds by Agroinfection. Samples of transgenic tobacco seeds, both milled and whole, were incubated with porcine gastric fluid, at 38° C in Dubnoff Shaker for 1, 2 and 3 hours. After gastric fluid removal, by centrifugation and washing with PBS, samples were homogenized in the presence of protein extraction buffer. Western blot was performed on representative samples of extracted proteins, quantified by Bradford method, using rabbit polyclonal serum. The Vt2e-B specific signal was observed in all samples derived from transgenic tobacco seeds. Nevertheless, from 0 h to 3 h, a progressive reduction of intensity of signal was observed. No significant differences were detected on the reduction of signal intensity between samples derived from whole and milled tobacco seeds.