Genes for peptide epitopes of pathogen can be used for the production of vaccines against a variety of human and animal diseases. This concept of vaccine production in transgenic plants was introduced in 1992. In the year 1995, biopharmaceutical company ProDigene from Texas (USA) conducted clinical trials, where pigs, fed with an edible maize vaccine, were found protected against the transmissible Gastroenteritis virus.
The company had also taken patent on this and other edible vaccine produced in transgenic crops. Such vaccines, whenever successful, will provide a technology for production and delivery of inexpensive vaccines, especially in the developing world. This technology will also be cheaper than expensive Recombinant cell culture based expression systems.