Vaccine Cuisine Could Soon Grace Your Table
Aug. 11, 2000 -- It's vaccination time, but no needles are needed. You hand your child's prescription to the pharmacist, and she gives you a bottle of tomato juice -- or applesauce, or spinach, or rice, or maybe a dried vegetable powder. Today, bio-engineered plants are being used as inexpensive factories to manufacture vaccine ingredients. Tomorrow we may be eating the plants themselves.
By infecting them with genetically altered plant viruses or bacteria that can't cause disease but can reproduce, scientists can make plants produce large quantities of many different kinds of substances -- including vaccines.
The idea fascinates vaccine pioneer Hilary Koprowski, a key player in the development of the oral polio vaccine and inventor of the modern rabies vaccine. Koprowski has been working on plant-derived vaccines for the past decade. He is now director of the Biotechnology Foundation Laboratories and the center for neurovirology at Jefferson Medical College at Thomas Jefferson University in Philadelphia.
"Why plants? Three things," Koprowski tells WebMD. "Reason No. 1 is extremely good safety -- there is nothing in plants that can contaminate the vaccine [and make humans sick]. The plant viruses we use cannot infect mammals, including humans. Second, the cost. You do not need a factory to grow a plant. Third, the ease of distribution. You could easily make a freeze-dried vegetable powder."
It's not science fiction. One virus on the defensive is respiratory syncytial virus, or RSV -- the single most important cause of respiratory infection in infants and children throughout the world, which causes an illness commonly referred to as croup. An injectable vaccine against RSV was a spectacular failure -- vaccinated children actually got a worse disease because the vaccine stimulated the wrong kind of immunity. Dennis E. Buetow, PhD, and co-workers at the University of Illinois at Urbana-Champaign have created engineered cherry tomatoes that appear to elicit the right kind of immune responses in mice.
"Our idea is to prevent RSV infection," Buetow tells WebMD. "We are thinking that you would eat the fruit at some time preceding each RSV season. The reason we began with the cherry tomato is that we are thinking about the apple. Of course, growing fruit trees is a three- to five-year process, so we wanted to see whether it would work in cherry tomatoes first."
It won't take years to grow orchards in all cases. One firm -- Large Scale Biology Corp. -- already has built a factory capable of processing three tons of plant material per hour. "Plants will grow anything," Koprowski says. "The state of the art is that a large number of labs all over the world" are trying to use plants to produce a lot of vaccines, hormones, cancer fighting substances, and blood products. In 10 years you will have a lot of plant-derived human products available, predicts Koprowski.