Development of Edible Plant Vaccines

Plants are a promising platform for the production of vaccines. So far, several plant species suitable for the expression of recombinant proteins with technical and pharmaceutical value have been described. Obvious advantages of plant-derived vaccines are the convenient storage of the material, the lack of human or animal pathogens and the reduction of downstream processes. Storage tissues like cereal and legume seeds with high protein content and excellent storage qualities are favoured for the development of edible vaccines. However, low expression levels combined with the low immunogenicity of plant-derived subunit vaccines have often prevented the development and commercialisation of edible plant vaccines. Optimizations of plant expression systems for vaccine production are necessary to transfer the potential of transgenic plants into the medical market. Until now, there are only a few plant-derived vaccines close to commercialization, like the Concert™ Plant-Cell-Produced vaccine against the Newcastle disease virus (DowAgroSciences). Oral applications of plant-derived vaccines are the specific focus of this article. We emphasise the special demands of oral vaccines and the remaining challenges of edible plant vaccines.