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Tobacco: A Pharmaceutical Lab?

College of Agriculture and Life Sciences researchers are working to genetically engineer tobacco plants to produce a type of protein that can be used to make a vaccine that prevents the development of cervical cancer.

Research Assistant Yan Sheng Liu studies tobacco plants. Working with a scientist at Georgetown University in Washington, D.C., a team of College researchers is inserting into tobacco plants genes that produce proteins that may be used to make vaccines. The N.C. State team is made up of Dr. Rebecca S. Boston, Dr. Arthur K. Weissinger and Dr. Raymond C. Long.

Boston, Weissinger and Long are collaborating with Dr. A. Bennett Jenson, a clinical pathologist at the Georgetown University Medical School. Jenson has identified genes from the human papilloma virus and a similar canine oral papilloma virus that contain instructions for the production of proteins. The genes are part of the genetic makeup of the two viruses.

The human papilloma virus causes the growth of cervical lesions in women. Left untreated, the lesions often develop into cervical cancer. The canine virus causes the growth of warts in the mouths of dogs. Jenson and the N.C. State team are using the canine virus as a model for their work with the human virus. They hope to use what they learn about the canine virus to produce a vaccine against the human virus.

Jenson has already developed a vaccine against the canine papilloma virus, but he has been unable to produce large amounts of the proteins needed to make the vaccine inexpensively.

That’s where Boston, Weissinger and Long come in. They hope to turn tobacco plants into miniature pharmaceutical labs to produce the proteins needed to make vaccines.

“It’s no problem to get the gene into the plant and to express the gene and to extract protein on a modest scale,” Weissinger said. “But can we extract enough protein to make it economically inviting?”

Funding for the project has been provided by the Albert B. Sabin Vaccine Institute at Georgetown University and the U.S. Department of Agriculture.

Of particular concern to the developing world

Although the human virus is of increasing concern in the United States, a viral vaccine would probably have its greatest use in developing parts of the world.

The Pap smears that are part of regular medical checkups in developed nations usually catch growths caused by human papilloma virus before they become serious. In developing nations, however, women often do not have access to preventive medical care, and the growths caused by the virus go untreated, often becoming cancerous.

According to the World Health Organization, cervical cancer is the second most important cancer in women after breast cancer. Approximately 500,000 new cases are identified each year, and mortality is high. Nearly 300,000 women worldwide die each year from cervical cancer. Eighty percent of the deaths are in developing countries. The development of a vaccine against the virus would likely save many of these women.

A pharmaceutical future for tobacco farmers?

Long, a professor in the department of crop science, is an expert on producing tobacco for the extraction of protein and on extracting the protein. He sees in the project the potential to develop an additional use for tobacco, allowing North Carolina farmers to continue to grow tobacco as the state’s tobacco acreage and the profitability of growing the crop decline.

Tobacco, Long explained, already contains another protein called Fraction 1 that is used in the food and cosmetics industries.

“We think it’s likely that the cost of production of tobacco and the initial processing could be paid for with the isolation and sale of Fraction 1,” Long said.

But tobacco could also be engineered to contain other proteins, such as the protein used to make papilloma virus vaccine. Long sees farmers taking their profit from the sale of these additional proteins.

Long has for some years contended that the future of tobacco, at least in North Carolina, may be pharmaceutical in nature. He has even developed methods of growing tobacco that enhance protein production.

Experts on track to begin field tests

Long, Boston and Weissinger photoBoston is an expert on the structure and function of plant proteins as well as transformation systems, or genetic engineering techniques, designed to change the genetic makeup of plants so that protein production is altered. A professor in the department of botany, she also brings to the project expertise in designing tests or methods of tracking protein production in plants.

Weissinger’s expertise is also in genetic transformation. Much of his work involves genetic expression, working to ensure that genes continue to function properly after being moved from one organism to another and to maximize their expression. He is an associate professor in the department of crop science.

Having successfully engineered tobacco to produce the viral proteins, the N.C. State team is on schedule to begin field tests this year. The field tests are designed to produce proteins that can be used to make a vaccine against the canine papilloma virus and to allow tests of the efficacy of the vaccine. The field tests should also go a long way toward determining whether tobacco plants will provide amounts of viral protein sufficient to produce an affordable human papilloma virus vaccine.