Delivery of plant-derived vaccines

Many protein subunit vaccine candidates have been expressed in transgenic plants, and in a few cases the recombinant material has entered early phase clinical or target animal trials. The expressed protein can be purified prior to formulation for any preferred delivery approach. However, there are major cost advantages associated with avoiding protein purification and pursuing the oral delivery of a processed plant product containing the recombinant protein. Grains and dry products that are processed from fresh plant tissues can stably store expressed proteins for extended periods of time at room temperature, making refridgeration unnecessary during storage and distribution. Encapsulation of recombinant proteins in plant tissues guards against their rapid degradation in the gut, therefore facilitating the uptake and induction of appropriate immune responses. Early trial data with plant-based vaccine candidates has shown promising safety and efficacy.