Wednesday, June 27, 2001 By Stephen Leahy, Environmental News Network Recently the glare of the media spotlight has fallen on genetically engineered food crops bred to resist herbicides and insects. Meanwhile, plants engineered with human proteins to produce drugs and vaccines for human consumption have escaped notice.
Well, take note: At least 350 genetically engineered pharmaceutical products are currently in clinical development in the United States and Canada. Scientists believe that potent drugs and vaccines will soon be harvested just like wheat and corn.
Welcome to the new world of molecular farming.
In Canada, a genetically engineered tobacco plant made to produce Interleukin 10 will be tested to treat Crohn's disease, an intestinal disorder.
Molecular farming uses the science of genetic engineering to turn ordinary plants into factories that produce inexpensive drugs and vaccines.
Researchers at the London Health Sciences Center in London, Ontario, Canada, are growing potatoes that have been genetically altered to produce a special diabetes-related protein. When the potatoes were fed to diabetic mice, scientists found that most don't develop Type I diabetes, also known as juvenile-onset diabetes.
Scientists believe that the low-cost production of this protein may help the 100 million people worldwide affected by diabetes.
In the lab, the new transgenic potatoes produce large amounts of a human protein that suppresses the destructive immune response and prevents diabetes from developing. Molecular biologist Shengwu Ma of the London Health Sciences Center says his team's research has similar potential to combate other autoimmune diseases such as multiple sclerosis, rheumatoid arthritis, lupus, and even transplant rejection.
Once the technology is perfected, growing transgenic potatoes will be inexpensive.
"Plants are ideal because they can synthesize and assemble proteins to provide huge quantities of soluble proteins at relatively low cost," says Ma. Many traditional drugs are difficult to make and hence, costly. However, once this technology is perfected, growing transgenic potatoes will cost very little, he notes.
Edible vaccines were first tested on humans in 1997, when scientists asked volunteers to eat anti-diarrheal transgenic potatoes produced by the Boyce Thompson Institute at Cornell University. After consuming the potatoes, almost all the volunteers produced antigens in their bodies just as if they had received a traditional anti-diarrheal vaccination. And they experienced no adverse side effects.
Research scientist Hugh Mason says volunteers are also testing raw potatoes engineered to produce a Hepatitis B antigen at the Roswell Park Cancer Institute in Buffalo, N.Y. Results are expected this summer.
Hugh Mason, an associate research scientist in edible vaccines at the Boyce Thompson Institute, hopes to develop "methods to increase production of foreign protein in plant cells and to engineer protein antigens that will enhance their potential as human and animal vaccines."
This fall Mason hopes to do human tests on Hepatitis B antigens grown in transgenic tomatoes, if the FDA approves. "This technology will be a big plus for the developing world," he says.
Not everyone is convinced that transgenic medicine delivered through food is a smart alternative. Though these edible vaccines seem beneficial, the spread of these novel genes into the environment could be a disaster, says biotech critic and retired professor of genetics, Joe Cummins.
He worries that, with current methods, transgenic plants produce human proteins in every cell of the plant, including the roots. Some of the plant matter is bound to get into the soil and ultimately into ground or surface water. Even if only minute quantities of these biochemically active proteins escape into the natural environment, the consequences could be great, he says.
As with other biotechnology, the long-term effects of transgenic plants on the environment are unknown.
Other concerns include the spread of transgenic material through pollen movement, insects and wildlife feeding on the plants, and accidental mixups of seeds, says Michael Hansen, a researcher for the Consumers Union, the nonprofit publisher of Consumer Reports magazine. "Will the transgenes be picked up by soil bacteria or viruses? No one knows yet," he says.
Cummins says many scientists in this field are "true believers" in the technology and often make assumptions about safety. In this case, assumptions can be "more threatening than terrorists," he says.
For now, the question remains: Will we risk unknown environmental hazards in the face of the growing demand for cheap, life-enhancing drugs and vaccines produced by molecular farming?
www.enn.com/news/enn-stories/2001/06/06272001/vaccines_43...
Original: enn: Edible vaccines