• Open Access

Tomato is a highly effective vehicle for expression and oral immunization with Norwalk virus capsid protein

Authors

  • Xiuren Zhang,

    1. Department of Plant Biology, Cornell University, Ithaca, NY 18853-1801, USA
    2. Boyce Thompson Institute for Plant Research, Inc., Tower Road, Ithaca, NY 14853-1801, USA
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  • Norene A. Buehner,

    1. Boyce Thompson Institute for Plant Research, Inc., Tower Road, Ithaca, NY 14853-1801, USA
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  • Anne M. Hutson,

    1. Department of Molecular Virology & Microbiology, Baylor College of Medicine, Houston, TX 77030, USA
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  • Mary K. Estes,

    1. Department of Molecular Virology & Microbiology, Baylor College of Medicine, Houston, TX 77030, USA
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  • Hugh S. Mason

    Corresponding author
    1. Boyce Thompson Institute for Plant Research, Inc., Tower Road, Ithaca, NY 14853-1801, USA
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    • Present address: Biodesign Institute and School of Life Sciences, Arizona State University, PO Box 875401, Tempe, AZ 85287-5401, USA


  • Data deposition: The sequence of sNVCP reported in this article has been deposited in the GenBank database (accession no. AY360474).

* Correspondence (fax +1 480 727 694; e-mail hugh.mason@asu.edu)

Authors e-mail: Xiuren Zhang zhangxi@rockefeller.edu; Norene Buehner nab28@cornell.edu; Anne Hutson ah692217@bcm.tmc.edu; Mary Estes mestes@bcm.tmc.edu.

Summary

Norwalk virus (NV) is an important agent of epidemic gastroenteritis, and an oral subunit vaccine shows potential for protection. Recombinant Norwalk virus (rNV) capsid protein expressed in plants assembles virus-like particles (VLPs) that are orally immunogenic in mice and humans. In this article we examine rNV expression in tomato and potato using a plant-optimized gene, and test the immunogenicity of dried tomato fruit and potato tuber fed to mice. The synthetic gene increased rNV expression fourfold in tomato and potato plants, which assembled VLP. Four doses of 0.4 g freeze-dried tomato fruit containing 64 µg rNV (40 µg VLPs) induced NV-specific serum IgG and mucosal IgA in ≥ 80% of mice, while doses of 0.8 g elicited systemic and mucosal antibody responses in all mice. Feedings of 1 g freeze-dried potato tuber containing 120 µg rNV (90 µg VLPs) were required to produce 100% responsiveness. Oxidation of phenolic compounds upon rehydration of dried tuber caused significant VLP instability, thus decreasing immunogenicity. Air-dried tomato fruit stimulated stronger immune responses than freeze-dried fruit of the same mass, perhaps by limiting the destruction of plant cell matrix and membrane systems that occurs with freeze-drying. Thus, rNV in dried transgenic tomato fruit was a more potent immunogen than that in dried potato tubers, based on the total VLPs ingested. These findings support the use of stabilized, dried tomato fruit for oral delivery of subunit vaccines.

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