[MucoRice: development of rice-based oral vaccine]

Parenteral vaccines are used commonly against most of infectious diseases. It is noted that these injection type vaccines are meant to induce protective immunity in the systemic compartment but not aimed at use of the benefits of mucosal immunity as a first line of defense against mucosal infectious diseases such as AIDS, SARS and Influenza. In addition, one of major practical obstacles to current vaccination is storage of the vaccine under refrigeration (or cold-chain) in the developing countries. To overcome these concerns, a plant-based vaccine is considered to be an attractive strategy. Currently, we have developed a rice-based oral vaccine that offers significant advantages over available vaccines. In the rice-based vaccine MucoRice, cholera toxin B subunit (CTB) as the vaccine antigen was accumulated in protein bodies as rice seed storage organella. When orally fed, rice seeds expressing CTB were taken up by the M cells covering the Peyer's patches (PPs), and inducing toxin-specific serum IgG and mucosal IgA antibodies with neutralizing activity. Further, MuocRice CTB remained stable state and maintained immunogenicity at room temperature for 1.5 years and was protected from pepsin digestion in vitro. Taken together, these findings suggest that MucoRice does not require needle/syringe and cold-chain but induces two layers of immunity in both mucosal and systemic compartments, which is the most effective and highly practical global vaccine to combat emerging and re-emerging infectious diseases.