Jam-Free Peanut Butter
Curing peanut allergies through genetic engineering
Peanut butter and jelly sandwiches, peanut brittle, and peanuts— what
do these three treats have in common? These are all foods that those
with peanut allergies cannot enjoy. In the United States, one of the
most common food allergies is to peanuts, making its study a practical
model for future allergy research. In anaphylaxis, which is the most
severe case of a hypersensitive allergic reaction, the lips, face, neck
and throat may experience swelling, and a flushed appearance with
itching and hives may occur. In an effort to bring relief to the peanut
allergy-afflicted, researchers have recently proposed the development
of genetically engineered peanuts to eliminate allergens,
allergy-causing agents, directly from the source.
According to a July 2007 online article in Medical News Today, Mohamed Ahmedna, PhD, North Carolina Agricultural and Technical State University, has discovered a method to create peanuts sans allergens. This method uses an edible fungus to ferment whole and ground peanuts, resulting in reduced allergen-protein levels. The precise mechanism for this fermentation has not been fully explained in Ahmedna’s article, but current yeast studies provide a good analogy. Fermentation of the yeast fungus is not a novel concept as it has been used commercially to produce beer, wine, and bread. During anaerobic respiration, which occurs in the absence of oxygen, yeast breaks down a macromolecule, usually a sugar, into ethanol and carbon dioxide. By a similar method, peanut allergen proteins are broken down by the fungus. According to Ahmedna, an immunoassay, a biochemical test determining the amount of a substance present by using antibodies, revealed that the fermented whole roasted kernels had 100 percent allergen inactivation. The processed peanuts were then tested in vitro with human serum from sufferers of severe peanut allergies, and the results produced no allergic reaction.
A separate study conducted by Hortense Dodo, PhD, Alabama A&M University, describes another method of eliminating the peanut allergen. In the September 2007 issue of Plant Biotechnology Journal, Dodo used genetic engineering to silence the peanut allergen gene. The mechanism in Dodo’s study involves ribonucleic acid interference (RNAi), which slices messenger RNA to turn off a gene that would normally be expressed after protein biosynthesis. At the molecular level, the peanut allergy involves the binding capacity of Immunoglobulin E (IgE), an antibody of the host immune system, with its corresponding allergen on the peanut.
Dodo and colleagues used RNAi to transform peanut tissues and silence the Ara h 2 allergen gene, which is responsible for causing allergic symptoms such as hives, swelling, and respiratory complications. In a person with peanut allergies, IgE binds to allergens such as Ara h 2, and the immune system responds with an allergic reaction. Dodo’s RNAi-treated Ara h 2 exhibited a significant decrease in its IgE binding capacity, equating to fewer problems for those afflicted with peanut allergies.
Beyond genetically engineered peanuts, immune response treatments are progressing and a few have even been successfully tested on humans. Anti-IgE therapy, for example, “showed some protection in the majority of peanut-allergic patients treated,” states Hugh Sampson, PhD, Professor of Allergy and Immunology at the Mount Sinai School of Medicine. In a study published in the March 2003 issue of New England Journal of Medicine, Donald Leung, MD, PhD, and his colleagues injected patients with TNX-901, an experimental drug that prevents minor allergic reactions. After patients were thus treated, they displayed fewer allergy symptoms after peanut consumption.
Since no cures for peanut allergies exist, current treatments have little or no lasting effect. However, hope is on the horizon as allergen-free peanuts await approval by the Food and Drug Administration for public consumption. Furthermore, procedures such as Ahmedna’s fungus fermentation and Dodo’s RNAi technology are both possibilities towards eradicating the peanut allergen. As new information and technology arise, even more effective methods may arrive to help eliminate the peanut allergy. Additionally, genetic engineering can also be used to make the peanut consumer immune to the peanut allergen. This leaves food scientists with many more options with which to silence the peanut allergy once and for all, and perhaps even other types of food allergies, as well.
About the Author
Brian Ichihara is a third-year Molecular and Cell Biology major and hopes to be a doctor in the future.