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Transgenic tobacco could lead to pharmaceuticals

By David Nutter

Spectrum Volume 20 Issue 34 - July 2, 1998

Virginia Tech will soon begin the first phase of a $754,000 state-funded research project that could lead to a tobacco-based industry for growing human pharmaceuticals in fields across Virginia.
A team of Virginia Tech scientists has demonstrated the feasibility of producing human therapeutic proteins in genetically engineered "transgenic" tobacco plants. Now, researchers will develop the special methods required to grow the transgenic tobacco that could bring new, high-value use to hundreds of acres of tobacco land state wide.
"This investment in biotech research will help lay the foundation for a whole new tobacco-based industry for Virginia," said Carole Cramer, project director and professor of plant pathology and physiology at the Fralin Biotechnology Center.
Planning began in early May for the first phase of a multi-year field trial. Researchers will eventually plant tens of thousands of transgenic tobacco seedlings in fields at the university's agricultural research stations at Blackstone and Glade Springs. These studies will also include greenhouse experiments and laboratory analyses on campus.
With the support of state Sen. William Wampler Jr. of Bristol, governors George Allen and Jim Gilmore included $554,000 over the biennium for transgenic medicinal-tobacco research. During the recent legislative session Wampler sponsored an amendment which earmarked additional funds specifically for the field trials.
"The General Assembly was pleased to add an additional $200,000 to assist in the expansion of research in the pharmaceutical uses of tobacco," Wampler said. "We look forward to reviewing the results of the practical application of transgenic-tobacco research, and we are hopeful that this research will result in new, viable economic opportunities for growing tobacco in our region."
Cooperating in the studies are scientists at CropTech Corporation, a plant biotechnology company located in Blacksburg. CropTech will contribute its proprietary know-how and transgenic tobacco lines, as well as laboratory facilities and financial resources from federal and private sources.
CropTech recently won a multi-year $8.8-million contract from the Advanced Technology Program of the U.S. Department of Commerce. That contract will allow CropTech to further develop technologies to support commercialization of transgenic tobacco for bio-production of pharmaceutics. A portion of the contract funds will support research at Virginia Tech and will match the support from the legislature.
Cramer said the tobacco biotechnology being developed at Virginia Tech is uniquely suited for pharmaceutical production. The plants are modified to contain a human gene--a tiny piece of human DNA with the information to build a human protein--but the gene cannot be "turned on" until the scientists give it a specific signal or inducer. Thus, the process can be controlled so that drugs will be made only after the leaves have been harvested and taken to a regulated manufacturing facility.
This summer's field tests are designed to begin designing methods farmers will eventually use to grow the transgenic pharmaceutical tobacco plants for commercial sale. Among the issues being investigated are optimal plant density, planting and harvest methods and timing, nutritional requirements and pest protection, Cramer said. Also being studied are conditions that could help maximize pharmaceutical production and maximize the extraction of the target compounds from the leaves of the plant.
Cramer said tobacco is exceptionally suited for use in producing pharmaceuticals because it is one of the most productive crops in growing leaf bio-mass quickly and efficiently. It is also one of the easiest plants to genetically modify. As a very prolific seed producer, it will allow production to be scaled up very rapidly.
Although greenhouse studies during this year will include drug-producing plants, the field tests for these lines will not begin until next year, Cramer said. This year's field tests will incorporate a "reporter gene" to enable scientists to rapidly assess the performance of transgenic tobacco under various growing conditions.
The trials will also explore the potential of using floating-bed greenhouse systems for producing transgenic tobacco.
"This technology has tremendous potential as a win-win situation for both tobacco producers and drug companies," Cramer said. "People will be surprised at how fast this new industry will be growing and the impact that it will have."