Peanut gene breakthrough may lead to allergen free nuts
protein with no apparent allergic effects, research that opens up
the possibility of allergen-free GM nuts.
The identification of the new gene, called ara h 3-im, by researchers from the University of Florida offers some hope for estimated 2.5 million people in Europe and the US now vulnerable to the food allergy.
"If it is true that Ara h 3-im has lower allergenic properties than other Ara h 3 proteins, this study may provide the information necessary to produce a hypoallergenic peanut through silencing of the major allergens and selecting for the reduced allergenic polypeptides via mutational breeding and/or genetic engineering," wrote authors I-H Kang and M. Gallo.
While it is too early to tell if such a peanut will be available for the food industry in the foreseeable future, escalating incidences of food allergies in Europe and the desire to avoid potentially harmful consumer confusion underpinned changes to the Labelling Directive 2000/13/EC due to enter into force this month that essentially flag up to the consumer possible allergens in a food product.
The amendment heralds the mandatory inclusion on food labels of the most common food allergen ingredients and their derivatives: cereals containing gluten, fish, crustaceans, egg, peanut, soy, milk and dairy products including lactose, nuts, celery, mustard, sesame seed, and sulphites.
There is no current cure for food allergy and vigilance by an allergic individual is the only way to prevent a reaction but a peanut allergy can be so severe that only very tiny amounts can be enough to trigger a response.
"Although about 20 peanut allergens have been reported, Ara h 1, Ara h 2 and Ara h 3 are classified as important major allergens which are recognized by more than 50 per cent of peanut allergic patients," explained the researchers.
"Ara h 1 and Ara h 2 are recognized by 70 to 90 per cent of patients with peanut allergy, and Ara h 3 is recognized by serum immunoglobulin E from approximately 44 to 54 per cent of different patient populations with a history of peanut sensitivity," they said.
The new research, published in the journal Plant Science, reports that a previously unidentified complementary/cloned DNA (cDNA) produces a protein with potentially reduced allergenicity.
The researchers report that Ara h 3-ims novel N-terminal sequence is different and distinct from the other allergens. This changes the proteins ability to bind to immunoglobulin E (IgE), an antibody that is capable of initiating powerful immune responses.
Using a technique called immunoblotting the researchers report that these distinct differences were translated into the Ara h 3-im polypeptide not being recognized by IgE, isolated from blood taken from peanut sensitive patients.
This opens up the opportunity to genetically modify or breed mutationally a peanut with the allergen Ara h 3 replaced by the non-allergen Ara h 3-im.
"Initial results indicate that Ara h 3-im has potentially lower allergenic properties than previously characterized peanut allergens which may aid in the production of a hypoallergenic peanut," concluded the researchers.
Significant further research is needed, but one of the main challenges to the continued development of this technique will be consumer acceptance, particularly in Europe, and most notably in the UK, if the research follows the genetically modified route.
Source: Plant Science Article in press published on-line ahead of print. doi:10.1016/j.plantsci.2006.09.014 Cloning and characterization of a novel peanut allergen Ara h 3 isoform displaying potentially decreased allergenicity Authors: I.-H. Kang and M. Gallo
