Vaccine technology: based on the use of modern immunology to develop recombinant DNA vaccines for improved disease control against lethal diseases. Edible vaccine research is currently directed at human diseases, with a special emphasis on the developing world. The technology will also have immediate value for the production of inexpensive vaccines as feed additives for agricultural animals. Since various plant tissues are fed to animals, other plants such as alfalfa, maize and wheat could be valuable vehicles to deliver vaccines (and perhaps other pharmaceuticals) for the betterment of animal health.

DNA vaccines work like this: Pure DNA is taken from disease cells and injected into the body just like a regular vaccine. The vaccine then produces a protein that triggers the formation of cytotoxic, or killer, T-cells. Because the protein is formed in the body instead of in a lab, the T-cells “know” which viral cells to target. This targeting ability is what makes DNA vaccines more effective than traditional vaccines.

Living Examples
Hepatitis B virus (HBV) infection is probably the single most important cause of persistent viremia in humans. The disease is characterized by acute and chronic hepatitis, which can also initiate hepatocellular carcinoma. The prevalence of this disease in developing countries justified initial efforts to express HBV candidate vaccines in plants. Currently, two forms of HBV vaccines are available, both of which are injectable and expensive: one purified from the serum of infected individuals and the other a recombinant antigen expressed and purified from yeast. We have transformed plants with the gene encoding the hepatitis B surface antigen (HBsAg); this is the same antigen used in the commercial yeast-derived vaccine. An antigenic spherical particle was recovered from these plants which is analogous to the recombinant hepatitis surface antigen (rHBsAg) derived from yeast. Parenteral immunization of mice with the plant-derived material has demonstrated that it retains both B- and T-cell epitopes, as compared to the commercial vaccine.
DNA Vaccine Human Trials: Malaria, HIV, Melanoma, Lymphoma, Influenza, Hepatitis B, Herpes and Tuberculosis