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Tobacco research may provide cure

By Stewart MacInnis

Spectrum Volume 18 Issue 16 - December 14, 1995

This rare bit of good news for the beleaguered tobacco plant was delivered from laboratories at Virginia Tech and at the Virginia Tech Corporate Research Center recently: Genetically engineered tobacco may become the source for a human enzyme that is used to make what to now has been considered the world's most expensive drug.

On the heels of that good news came the dedication of the Horace G. Fralin Biotechnology Center on the Virginia Tech campus. The center is designed to provide a focal point on campus for multi-disciplinary research in the evolving field of biotechnology.

The tobacco announcement illustrated the whole point of biotechnology and the purpose of the Fralin Center: To use biological processes for commercial purposes and, at the same time, to benefit society.

Carole Cramer, associate professor of plant pathology and physiology in the College of Agriculture and Life Sciences, announced this fall that she and fellow researchers had produced the human enzyme glucocerebrosidase in transgenic tobacco. The enzyme is defective in patients suffering from Gaucher disease, a rare and potentially devastating genetic disorder.

"This is the first time an active human enzyme that shows correct enzymatic activities has been produced in a plant," said Cramer, who is also vice president for research for CropTech Development Inc., a small research firm at the Corporate Research Center.

Tobacco is used because its biology is easily manipulated for the introduction of new genes and the production of "foreign" proteins. Researchers inserted into the DNA of the plant that portion of human DNA that directs the production of glucocerebrosidase. This new DNA, or "transgene," directs the plant to produce the human enzyme, which is then removed from the tobacco leaves.

Laboratory testing shows the enzyme produced in the tobacco plant acts the same as the enzyme produced in the human body. Cramer said the next step is clinical trials, which she hopes will begin in three to five years.

David N. Radin, president of CropTech and a former faculty member of the College of Agriculture and Life Sciences, said it is too early to estimate the cost of producing the drug to treat Gaucher disease using tobacco-produced enzymes. The process, however, should result in a drastic reduction in the price of the drug, which now can be as much as $300,000 per year for each patient, he said.

The cost is so high because the enzyme is currently purified from human placenta, with 2,000 to 8,000 placentas required to create a single dose of the drug. Cramer said one tobacco plant is expected to provide enough of the enzyme for at least one dose, and possibly more.

While the potential for another, cheaper source of the drug is good news for the estimated 2,000 Americans with Gaucher disease, Cramer said the techniques and understanding developed in the process are what is really exciting.

"This indicates that other enzymes can be produced, too," she said. "In fact, CropTech is working on other drugs and therapeutics right now."

Tracy Wilkins, director of the Fralin Center, expects the biotechnology center to help researchers in similar efforts to bridge the gap between science and business.

"Our vision is that the center will be involved in training as well as education," he said. "Biotechnology is the application of science. We will show students how to put science to actual use."

Some of the seven faculty members who maintain offices and laboratories in the Fralin Center also work for or helped found companies in the Corporate Research Center.

"This direct experience in entrepreneurship allows the faculty to impart real-world experience to students," Wilkins said. "The center interacts with these Virginia companies to enhance technology transfer and increase the competitiveness of Virginia's biotechnology industry."