oping nations (Landrige 2000). In 1995 Arntzen and his researchers had introduced into tobacco plants the gene for a protein derived from the hepatitis B virus, and had gotten the plants to synthesize the protein (Landrige 2000). They then injected the antigen into mice, and it activated the same immune system components that are activated by the virus itself. However injection is not the aim, feeding is. In the past five years experiments conducted by Arntzen and his group at the Boyce Thomson Institute for Plant Research at Cornell University, and the group at Loma Linda University have demonstrated that tomato or potato plants can synthesize antigens from the Norwalk virus, enterotoxigenic E. coli, V. coli, and the hepatitis B virus (Landrige 2000). Also, feeding antigen-laced tubers or fruits to test animals can evoke mucosal and systemic immune responses that fully or partly protect animals from subsequent exposure to the real pathogens or to microbial toxins. Edible vaccines have also provided lab animals with some protection against the rabies virus, Helicobacter pylori (a bacterial cause of ulcers) and the mink enteric virus (which does not affect humans) (Landrige 2000). The way the edible vaccine provides protection is in the way the digestive tract takes up the vaccine (Landrige 2000). It is the rough outer wall of plant cells that serves as temporary armor for the antigens, keeping them relatively safe from gastric secretions. When the wall finally begins to break up in the intestines, the cells gradually release their antigenic cargo (Landrige 2000). An antigen in the food vaccine gets taken up by M cells in the intestine, and passed to various immune-system cells, which then launch a defensive attack (Landrige 2000) One way of generating edible vaccines relies on the bacterium Agrobacteruim tumefaciens to deliver into plant cells the genetic blue prints for viral or bacterial antigens (Landrige 2000).The key to e...
