Transgenic plants for mucosal vaccines

This chapter discusses the advances in the field of transgenic plant-derived mucosal vaccines, focusing on the results of human clinical trials and on orally delivered animal vaccines. The transgenic plant-derived vaccine antigens are known to be orally immunogenic in humans and several animals species. The choice of crop for production of vaccines has a direct bearing on the ability to contain transgenes, with pollen-shedding crops presenting a greater challenge than those like tomatoes or other self-pollinating species. Strategies for monitoring genes within the environment are employed, such as use of dominant marker genes, high-resolution detection systems, and efficient production, processing, and monitoring systems. Ingestion of transgenic plants expressing vaccine antigens can, via the gut lymphoid system, result in specific mucosal secretory IgA (S-IgA) and serum IgG antibody responses. Swine transmissible gastroenteritis (TGE) is an economically important herd health problem globally. It is a highly contagious viral diarrheal disease in neonatal pigs. Swine TGE is caused by the transmissible gastroenteritis virus (TGEV), a coronavirus with an immunodominant spike (S) protein. Studies of immunization of mice intramuscularly with crude plant extracts induced TGEV-specific antibodies. The results indicated that the plant-expressed S protein presents virus-neutralizing epitopes and is thus a competent immunogen.