Edible Plant Vaccines are only 2-4 years from Full Development
In the December issue of Genetic Engineering News, (vol. 21, # 21:p. 40 & 71), Vicki Brower writes about what Plant Biotechnology has achieved so far by way of enhancing crop yields, creating edible plant vaccines etc. in an article entitled, "Harnessing the Potential of Plant-Based Biotech." The author describes the research results of Professor Alexander Karasev and his team at Jefferson Medical College in Philadelphia.
Using spinach, lettuce and soybeans the team has reported promising results in developing edible vaccines for HIV and hepatitis B. Besides being much cheaper, plant vaccines are safe and in a matter of time will be within the purchasing capacity of average citizen in developing countries. Using tobacco mosaic virus (TMV), the group expressed the Trans-Activating Transduction (TAT) gene in the leaves of Nicotania benthamiana and spinach. However, they found it necessary to fuse the tat protein to plant virus capsid proteins in order to obtain symptoms in the treated plants in the form of leaf curling, yellowing and stunting of growth. Extractable tat protein from leaves fully retained immunological reactivity against tat-specific monoclonal antibodies.
The group has embarked another project in which they have incorporated the cloned gene into the lettuce genome in order to produce the recombinant hepatitis B vaccine. Volunteers, who ate the vaccine-containing lettuce, showed immunity against this deadly disease.
Another vaccine project, the group has been working on, is the development a rabies vaccine. The volunteers, who were given spinach containing the vaccine, showed a good antibody response. According to the author, these plant vaccines are about 2-4 years from full development.
