DENVER--Peanuts cause one of the most common--and most deadly--food allergies. Now, plant biologists have attempted to create the first hypoallergenic peanut through genetic engineering. The group reported its progress here 8 March at the annual meeting of the American Academy of Allergy, Asthma and Immunology.
In the United States, roughly 1.5 million people are allergic to peanuts. The allergy typically develops during childhood and usually lasts a lifetime. Even tiny amounts of peanut or peanut oil can trigger a reaction. It's among the most serious of allergies; 90% of deaths caused by severe food reactions are nut-related.
By silencing the genes that account for the three major allergy-causing proteins in peanuts, researchers at Alabama A&M University in Normal hope to grow safer peanuts. Hortense Dodo, a food molecular biologist on the team, says other attempts to solve the problem, such as immune therapy or vaccines, have failed so far (but see ScienceNOW, 10 March). Instead of focusing on the patient's reaction to peanuts, she says, "why not go after culprit itself--the allergens coded by peanut genes?" An allergen-free peanut would help reduce the risk of accidental ingestion by allergy sufferers.
At the meeting, team member Koffi Konan, a plant molecular biologist, showed how the plants were made by inserting shortened or backward versions of each of the genes--Ara h1, Ara h2, and Ara h3--into cultured cells from peanut plants. Plants grown from these cells make abnormal versions of messenger RNA, the molecule used to make the proteins. These abnormal RNAs trick the plant into destroying the corresponding normal RNA, thus silencing the normal genes. So far, the group's plants look and grow like normal peanut plants but have not yet produced seeds. Konan says infertility is common in plants grown from cultured cells, but he says that by the end of the year he should have peanuts to test, if all goes well.
Others working on genetically modified (GM) peanuts say that's a big "if." Gary Bannon, a biochemist at the food biotechnology company Monsanto in St. Louis, Missouri, says this approach is tricky. Ara h1, Ara h2, and Ara h3 are three of the major genes that peanut plants use to store seed protein. If you silence them, he says, "you might not have a peanut." He and others believe that the only way to get allergen-free nuts will be to add back non-allergenic seed storage genes after silencing the original copies.
Meeting Web site of the American Academy of Allergy, Asthma and Immunology
Alabama A&M's Department of Food and Animal Science
Food allergy fact sheet from the National Institute of Allergy and Infectious Diseases