Avian influenza, an acute viral infectious disease that occurs in poultry such as chickens, ducks, and migratory birds, has been reported to be transmittable to humans. It is difficult to control because it spreads among migratory birds that travel to China, Europe, and elsewhere. Once it is transmitted, it spreads rapidly. Disposing of infected livestock is not only costly, but also a cause of serious environmental pollution. This is why vaccines against infectious diseases are imperative. To this end, a research team in Korea has recently developed a plant-based, adjuvant-free, recombinant protein vaccine that exhibits a strong immune response.