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Tobacco-A Killer Turned Hero

Tobacco may soon have its nasty reputation replaced with a more positive image-that of producer of health promoting products. This crop may help keep the population healthy. Genetic engineers have successfully introduced foreign genes into a variety of plants, including tobacco, using plant viruses as vectors. By placing the desired gene adjacent to an active viral promoter, the plant is tricked into producing large concentrations of the foreign protein. Plants thus have become another vessel for synthesizing foreign gene products along with bacteria, yeast and mammalian cells in culture.

Among the successful demonstrations of the technique have been the productions of an anti-AIDS drug and an antihypertensive protein by tobacco plants infected with a modified tobacco mosaic virus. The future is likely to bring other therapeutic protein, vaccine components and industrial enzymes.
Studies indicate several advantages that plants have over the conventional unicellular systems. They produce large volumes of protein that are more readily extracted and ultimately cheaper. These preparations are also free of many contaminating materials that pose problems in bacteria produced products (such as endotoxin) that might be harmful to humans. In addition to being safe, plant derived vaccines have often proved to be more effective than bacteria derived vaccines because of the way the antigen is assembled.
Plants may become a cost effective way to produce human or animals vaccines and may eventually provide a painless route of administration. Scientists are already trying to develop edible vaccines. By eating an antigen contains fruit or vegetable, children might someday be inoculated against the various pathogens that threaten their health. Alfalfa, Lettuce, and tomatoes are already producing vaccine components against cholera toxin and hepatitis B virus. The challenge now is to figure out ways to ensure that these proteins retain their antigenicity as they travel through the digestive tract and that their antigenic determinants can stimulate adequate immunity.

Glowing tobacco plant is the product of genetic engineering having grown from a tobacco cell that received a copy of the firefly gene that enables the insect to illuminate its abdomen. Just as the firefly gene is expressed when incorporated into this tobacco plant, genes for other products more useful to us than a glowing plant are expressed making the plant a factory for the desired product.
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