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

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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 exgenous CTB in trangenic 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.

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This research was supported by Natural Science Foundation in Guangdong Province of China (Grant No. 013075). Thanks are due to Prof. Zhong-Ju Xiao at Southen Medical University, China, Terry W. Hill at Rhodes College, TN, USA, and Dr. Chun-Quan Ou at HongKong University, China for providing valuable suggestions. The authors also wish to thank School of Life Sciences, Sun Yat-Sen University, where part of the experiments were conducted.

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Correspondence to Zhu-Mei He or Shou-Yi Yu.

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Xiao-Ling Jiang and Zhu-Mei He contributed equally to this work.

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Jiang, X., He, Z., Peng, Z. et al. Cholera toxin B protein in transgenic tomato fruit induces systemic immune response in mice. Transgenic Res 16, 169–175 (2007).

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  • Cholera toxin B
  • E8 promoter
  • Edible vaccine
  • Immunoglobins G and A
  • Transgenic tomato