Scientist-Gardeners Grow Plants That Hold Promise as Vaccines Researchers Targeting Cholera, Hepatitis B

Article excerpt

Most farmers sow fields of alfalfa and reap acres of salad greens. Mitch Hein is cultivating alfalfa sprouts that could stem a cholera epidemic.

In a locked vault behind a chain-link fence in a corner of an underground parking garage, Hein is tending a garden of unusually potent health food.

Hein is a cell biologist at the Scripps Research Institute. Each green plastic pot in his growth chamber contains a scraggly alfalfa seedling that he has genetically engineered to contain just enough of the deadly cholera toxin he thinks will confer immunity on anyone who eats enough of it.

Each plant is an edible vaccine: No need for purified, refrigerated serum or hypodermic needles. Just salad dressing.

While scientists at large biotechnology companies labor to improve supermarket tomatoes or create crops resistant to chemical sprays, a handful of researchers like Hein are transforming ordinary fruits and vegetables into unconventional medical vaccines that promise to revolutionize public health.

If these genetic gardeners are successful - and human clinical trials bear out their preliminary laboratory findings - an apple one day actually may keep the doctor away. Vaccinations against common diseases that kill tens of millions of people every year could involve no more than a slice of bread or a piece of home-grown fruit.

The researchers want to eradicate deadly diseases by simply giving people in developing countries the genetically engineered seeds that will sprout edible vaccines. They hope to reach the point where people who have no medical training, in villages far from hospitals or public health stations, would find tending to their health as easy as tilling a garden.

That day is years away, but scientists are making significant strides toward demonstrating that such plants are feasible. Last month, Hein harvested his first crop of the alfalfa vaccine from a small field in Ardmore, Okla. Now, 15 crates of sprouts are drying in a corner of his Southern California lab.

Biologists like Hein are seeking ways to link agriculture and human medicine. They have coupled advanced theories of how the body's immune system fights off disease with the latest in recombinant DNA technology.

They are trying to take advantage of the natural ability to build resistance against an illness through exposure to edible nontoxic compounds called antigens, isolated from a virulent virus or bacteria. The antigens provoke the antibodies that confer immunity without actually making you sick.

Charles Arntzen at Texas A&M University is trying to develop a banana that can prevent hepatitis B, an illness that strikes up to 300 million people worldwide.

Arntzen, a molecular biologist, already has produced a potato that prevents gastroenteritis. …