Cholera toxin B protein in transgenic tomato fruit induces systemic immune response in mice

Abstract

Cholera toxin B (CTB) subunit is a well-characterized antigen against cholera. Transgenic plants can offer an inexpensive and safe source of edible CTB vaccine and may be one of the best candidates for the production of plant vaccines. The present study aimed to develop transgenic tomato expressing CTB protein, especially in the ripening tomato fruit under the control of the tomato fruit-specific E8 promoter by using Agrobacterium-mediated transformation. Transgenic plants were selected using PCR and Southern blot analysis. Exogenous protein extracted from leaf, stem, and fruit tissues of transgenic plants was detected by ELISA and Western blot analysis, showing specific expression in the ripening fruit, with the highest amount of CTB protein being 0.081% of total soluble protein. Gavage of mice with ripe transgenic tomato fruits induced both serum and mucosal CTB specific antibodies. These results demonstrate the immunogenicity of the CTB protein in transgenic tomato and provide a considerable basis for exploring the utilization of CTB in the development of tomato-based edible vaccine against cholera. The rCTB antigen resulted in much lower antibody titers than an equal amount of exogenous CTB in transgenic fruits, suggesting the protective effect of the fibrous tissue of the fruit to the exogenous CTB protein against the degradation of protease in the digestive tracts of mice.

Optimization of regeneration and transformation parameters in tomato and improvement of its salinity and drought tolerance

“…In addition to these characteristics, tomato is one of the most important model systems for basic and applied research and can be easily propagated using either seeds, or clonally by tip or shoot cuttings. Recently, tomato was used as bioreactor in biopharming for the production and oral delivery of vaccines (Jiang et al, 2007) and as functional food for cancer prevention (Butelli et al, 2008). During the recent years, tomato has become the subject of new areas of intensive research such as: functional genomics, proteomics and metabolomics.…”

Transient expression of optimized and synthesized nattokinase gene in melon (<i>Cucumis melo</i> L.) fruit by agroinfiltration

“…Thus a transgenic product driven by such a promoter will concentrate in certain organs, like seeds or fruits, to limit any possible negative effects on plant growth and improve the harvesting efficiency. The fruit-specific E8 promoter from tomato has been used for the expression of Cholera toxin B protein (Jiang et al 2007). In this study, the expressions of the sNK gene controlled by 35S promoter and E8 promoter were different (Figure 3a, b).…”

Novel Transgenic Rice-Based Vaccines

“…Since 1990 researchers have developed several edible plant-based vaccines using bacterial antigens, such as the heat-labile toxin B subunit (LTB) from enterotoxigenic Escherichia coli, cholera toxin (CT) B subunit (CTB), and antigens from Yersinia pestis and viruses, such as hepatitis B virus, rotavirus, and Norwalk virus; these antigens were introduced into carrot, soybean, tomato, rice, potato, and tobacco (Jiang et al 2007;Li et al 2006;Moravec et al 2007;Nochi et al 2007b;Rosales-Mendoza et al 2008;Santi et al 2006;Thanavala et al 2005;Zhang et al 2006). Vaccines produced in plants have some advantages over traditional oral vaccines (which contain live, killed, or attenuated pathogens), including lower costs, a possibility of rapidly scaling-up production of the antigen protein, and no need for purification (Table 1).…”