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Focusing on the design of crops that will accumulate therapeutic compounds and vaccines in the leaves, fruits, grains, or storage tissue, they have been able to produce immunogenic proteins that can act as oral vaccines when ingested. These CIDV researchers have conducted successful Phase I clinical trials with plant-derived vaccines against hepatitis B, enterotoxigenic E. coli, and Norwalk virus. These vaccines have shown particular utility in preventing diarrhea—still one of the two top causes for child mortality worldwide.

Plant based vaccines could save millions of lives in developing nations. In addition to the obvious humanitarian benefits, vaccine production in crops affords other advantages including:

• The ability to produce pharmaceutical proteins and vaccines more economically than mammalian cell cultures or animal inoculation techniques.
• The ability to manufacture medicines for major diseases that cannot be produced in any other way.
• The efficiency of producing pharmaceuticals and diagnostic materials in large volumes to significantly increase patient access to new therapies.
• The natural ability to produce proteins with molecular structure similar to the proteins in the human body.

Many believe that plant-derived vaccines and therapeutics will be widespread in the next decade or two. For more than 13 years, scientists have been seeking out ways to produce proteins with which to treat animals and humans. To date, seven plant-derived antibodies or antibody derivatives have reached advanced stages of development. Analysts predict that more than 70 therapeutic monoclonal antibodies (MAbs) could be on the market by 2008 requiring production of more than 10 metric tons of MAbs annually. Today the 12 therapeutic MAbs that are approved for marketing are produced in mammalian cell culture facilities. But in the future, a plant-based approach may well be embraced as an efficient, high capacity alternative to traditional methods.