Making “Edible Vaccines” in Plants
Some scientists believe that vaccines could be produced in edible plants, such as bananas or potatoes, which would then provide the delivery vehicle. This approach would yield vaccines that are needle-free and require no adjuvants, chemicals that stimulate the immune response. When the plant is ingested, the plant cell walls would protect the vaccine antigens from degradation by stomach acid and digestive enzymes. Then in the intestine, the antigens would be released and transported into the circulatory system. Edible vaccines would stimulate both mucosal and systemic immunity, providing a higher level of protection than traditional vaccines.
Advocates claim that vaccines produced in edible plants would be low-cost and would not require refrigeration, making them more accessible to poor people in developing countries. But although several edible vaccines have entered clinical trials, none has yet been approved for marketing.5 Indeed, many technical questions remain to be answered before edible vaccines will become a viable option. Although a potato may express vaccine antigens, how many people will eat a raw potato? If the potato is cooked, will the vaccine remain effective? How does one ensure a uniform product or determine the appropriate dose?
Some scientists are now thinking of producing edible vaccines in bananas or potatoes and processing them into a powder, which would be more usable and consistent. It is not yet clear, however, if this approach is commercially viable. In any event, regulatory safeguards will be required to protect consumer health and the environment.