Expression of cholera toxin B subunit in transgenic tomato plants

Transgenic Res. 2002 Oct;11(5):447-54. doi: 10.1023/a:1020336332392.


Cholera toxin, secreted by Vibrio cholerae, consists of A and B subunits. The latter binds to G(M1)-ganglioside receptors as a pentamer (approximately 55 kDa). Tomato plants were transformed with the gene encoding cholera toxin B subunit (ctxB) along with an endoplasmic reticulum retention signal (SEKDEL) under the control of the CaMV 35S promoter via Agrobacterium-mediated transformation. PCR and Southern analysis confirmed the presence of the ctxB gene in transformed tomato plants. Northern analysis showed the presence of the ctxB-specific transcript. Immunoblot assays of the plant-derived protein extract showed the presence of cholera toxin subunit B (CTB) with mobility similar to purified CTB from V. cholerae. Both tomato leaves and fruits expressed CTB at levels up to 0.02 and 0.04% of total soluble protein, respectively. The G(M1)-ELISA showed that the plant-derived CTB bound specifically to G(M1)-ganglioside receptor, suggesting that it retained its native pentameric form. This study forms a basis for exploring the utility of CTB to develop tomato-based edible vaccines against cholera.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Agrobacterium tumefaciens / genetics*
  • Blotting, Northern
  • Blotting, Southern
  • Blotting, Western
  • Cholera Toxin / genetics*
  • Cholera Toxin / metabolism
  • DNA Primers / chemistry
  • Endoplasmic Reticulum / metabolism
  • Enzyme-Linked Immunosorbent Assay
  • G(M1) Ganglioside / metabolism
  • Gene Expression Regulation, Plant
  • Gene Transfer Techniques
  • Genetic Vectors
  • Lycopersicon esculentum / genetics*
  • Lycopersicon esculentum / metabolism
  • Plant Leaves / chemistry
  • Plants, Genetically Modified*
  • Plasmids
  • Polymerase Chain Reaction
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Receptors, Cell Surface / metabolism


  • DNA Primers
  • RNA, Messenger
  • Receptors, Cell Surface
  • ganglioside receptor
  • G(M1) Ganglioside
  • Cholera Toxin