Vaccine-Laced Food May Offer New Options for Doctors
People who ate chunks of a gene-engineered potato developed defenses against a diarrhea germ, raising doctors’ hopes of one day being able to vaccinate people with fruits and vegetables instead of needles.
The researchers didn’t test whether the vaccine actually gave protection. They just wanted to see if it could survive the digestive system and spur the body into making the proper defenses.
Apparently, it did. The specialized spud contained a protein that activated the immune systems of volunteers in the study.
Someday, researchers say, edible vaccines might fight such diseases as tetanus, hepatitis B, diphtheria and whooping cough. Scientists might even be able to combine several vaccines in a single food, said Dr. Carol Tacket of the University of Maryland School of Medicine.
“Wouldn’t that be great?” she asked. “You could just have your child eat a mashed-up banana in the pediatrician’s office.”
In developing countries, edible vaccines could also allow mass inoculations with locally grown food and without the expense of needles and trained personnel.
Tacket reported the potato study in the May issue of the journal Nature Medicine with Charles Arntzen of the Boyce Thompson Institute for Plant Research in Ithaca, N.Y., and others.
“When we started, a lot of people were pretty skeptical,” Tacket said. Now, she said, “we’re still surprised, but optimistic that this strategy might be useful in the future.”
The scientists targeted a form of E. coli bacterium that is a major cause of diarrhea in infants and tourists in developing countries. It’s different from the E. coli that made headlines recently for tainting hamburgers.
A particular protein in the germ provokes a strong response from the immune system when taken orally. So researchers developed a strain of potatoes with a gene added to make the spuds manufacture that protein.
Eleven healthy adults ate raw chunks of the potatoes three times over three weeks. Nearly all of them developed blood antibodies targeting the bacterial protein. Half had antibodies in their stools, indicating a response in the digestive tract.
Tacket said it is still not clear that an edible vaccine can reliably produce protection in the blood in addition to the stomach, as one would want for a malaria vaccine, for example. She also said that malaria, measles, German measles, mumps and HIV would not be initial targets for an edible vaccine because it is not clear what proteins to put in a food.
