Contact: Kay Kendall, (713) 677-7736, KKENDALL@ibt.tamu.edu
HOUSTON -- Spoons could one day replace needles as a way to administer vaccines to protect children against diarrheal diseases that kill millions each year in developing nations, researchers say.
Scientists at Texas A&M University's Institute for Biosciences and Technology (IBT) in Houston and Tulane University in New Orleans say laboratory animals fed genetically engineered potatoes produced antibodies against an infectious bacterium responsible for diarrheal disease.
This is the first time that an oral vaccination has been achieved by feeding a genetically modified plant, says Texas A&M molecular biologist Dr. Charles J. Arntzen.
Arntzen and his colleagues, Drs. Tariq A. Haq and Hugh S. Mason of the IBT and Dr. John D. Clements of the Department of Microbiology and Immunology in the Tulane Medical Center, described their findings in an article that appeared in the May 6 edition of the journal Science.
If the laboratory results translate into immunity against infection, Artnzen says, it could open the door to edible vaccines against enteric diseases caused by viruses or bacteria, such as cholera. These illnesses are blamed for the deaths of at least five million children each year in developing nations.
"In the developing world, a low-cost vaccine for these diseases would make a dramatic health improvement," Arntzen says.
Arntzen says that potatoes were genetically engineered to produce a protein subunit from an infectious variety of E. coli bacteria. When mice consumed the raw potatoes as food, they produced antibodies against the protein in both their blood serum and in secretions in the gut.
These results are "extremely hopeful, but not yet conclusive," Arntzen says. "Because mice do not get the human form of diarrheal diseases, we cannot determine protective immunity yet." Further tests in other animals that do get diarrheal disease are planned, he says.
Arntzen emphasizes that potatoes themselves are a good system in which to test the idea of edible vaccines, but probably will not be a practical way to administer them.
"The chances are that nobody is going to want to eat raw potatoes, and we believe that cooking is going to destroy the proteins that we're interested in, so we have to have something that's eaten raw."
Other members of Arntzen's research group are attempting to introduce the E. coli genetic material into other food plants, especially bananas.
"We're looking for something that could be eaten without cooking, and something that could be grown easily in developing areas of the world," he says. "Bananas seem to fill the bill."
"I don't see that every village in Africa or Latin America is going to have a pharmaceutical banana tree, because there might be disadvantages to eating this material on a repeated basis," Arntzen says. "I would see that if we are successful, this will be treated like any other pharmaceutical or herbal medicine and managed in a health care context."