Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: THURSDAY, November 25, 1993 TAG: 9311260035
SECTION: NATL/INTL PAGE: A-26 EDITION: HOLIDAY
SOURCE: ROBERT LEE HOTZ LOS ANGELES TIMES
DATELINE: SAN DIEGO LENGTH: Long
In a locked vault behind a chain-link fence in a corner of an underground parking garage, Hein, a scientist at the Scripps Research Institute, is tending a garden of unusually potent health food.
Each green plastic pot in the cell biologist's 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. At Washington University in St. Louis, biology professor Roy Curtis is engineering vaccines that use broccoli, turnips and Brussels sprouts.
Just to prove it could be done, Curtis developed tobacco that curbs tooth decay by serving as a vaccine against the bacteria responsible for dental cavities.
"What we are doing is oddball stuff in terms of what people think of as traditional research," Arntzen said.
Plants have long played a major role in medicine. About one-fourth of prescription drugs used in the United States owe their origins to plant substances, according to Brian Bloom, vice president of research at the New York Botanical Gardens.
As scientists have become frustrated by their inability to synthesize new drugs from scratch, they are increasingly rummaging through the botanical medicine chest.
Since 1991, researchers at the Missouri Botanical Garden have been collecting twigs, bark, flowers and fruit for the National Cancer Institute in tropical Africa and Madagascar. The material will be screened for potential anti-cancer and anti-HIV treatments. This fall, the New York Botanical Gardens began a $2 million prospecting project for Pfizer Inc. to scour the United States for plants that can serve as sources for new medicines.
With no natural remedy readily available for many diseases, some scientists are creating in the laboratory the plants that nature neglected to provide.
The research into edible vaccines holds particular promise for the public health of many developing countries, where such diseases as cholera - which are easily preventable through sanitation - kill as many as 10 million un-inoculated children every year, health experts said.
Until recently, cholera outbreaks could be readily controlled by antibiotics. But since 1980, cholera strains have appeared that are resistant to common antibiotics such as ampicillin, streptomycin and tetracycline.
An injectable cholera vaccine exists, but even inexpensive vaccines are beyond the reach of countries in which the annual public health expenditure averages $10 per person.
The newest recombinant DNA vaccines are expensive. A new injectable hepatitis vaccine is safer and more effective than conventional treatments, but it can cost up to $100 per person.
At the same time, AIDS and the potential for contaminated needles have turned inoculation into a significant health risk in some Third World countries.
The edible vaccines in development probably would be no more effective, but they would be cheaper and easier to distribute.
"We are on an idealistic quest," Arntzen said of his lab at the university's Albert B. Alkek Institute of Biosciences and Technology. "We have to come up with a way to deliver genetically engineered vaccines to places like Bangladesh, India, China and Thailand, in a production system that is appropriate for the Third World.
"The simplest thing is to give them a seed. Let them plant it, grow it and harvest it," he said.
That's why he thought of the banana.
"We wanted something you could feed uncooked to children. We wanted something that is easy to transport, not something that would need refrigeration," Arntzen said. "I challenge anyone to come up with something better than a banana."
by CNB