Hypoallergenic soybean can be created by use of natural mutant lines, genetic engineering for silencing allergen genes or chemical processing

Food allergy is estimated to affect between 5 and 8% of children (NHS Choices website), and allergy to soybean protein is one of the major contributors to this. Most sufferers will grow out of their soybean allergy, but the only form of management for the condition is currently to avoid exposure to the offending food, which can lead to nutritional difficulties. Scientists are experimenting with biotechnology techniques to develop hypoallergenic soybeans to which allergy sufferers may not be sensitive.

### A number of soybean proteins are allergenic
There are about 15 allergenic soybean proteins (Ogawa et al) of which three are considered to be major allergens. They are Gly m Bd 60K (a subunit of a major seed storage protein), Gly m Bd 30K (a glycoprotein similar to a house-dust mite allergen) and Gly m Bd 28K (another seed glycoprotein). Most patients suffering from soybean allergy will express sensitivity to at least one of these three allergens. Removing them from soybean products would therefore create a food which could be tolerated by most soybean allergy sufferers.

https://cdn.pixabay.com/photo/2017/04/26/22/24/soy-milk-2263942__340.jpg
image by pixabay.com

### Hypoallergenic foods can be created by chemical treatment
Some chemical treatments can be used to reduce the allergenicity of soybean products. For example, the process of extracting soy protein involves an acid and alkali extraction of de-fatted soybean or the use of hot aqueous ethanol (Jackson et al). Commercially produced soybean protein extracts have been shown to display reduced allergenicity. Reduced levels of soybean allergens can also be achieved through enzymatic digestion (Ogawa et al, 2000).

### Development of transgenic lines may reduce allergenicity
Samota et al identified a naturally-occurring mutant soybean line in which the allergens Gly m Bd 28K and Gly m Bd 60K were not expressed. The mutant line is called Tohoku 124, and studies of the line showed that the deletion of the allergenic proteins had no effect on the growth or survival of the plants. However, the mutant line still expresses the third major allergen, Gly m Bd 30K, which has been shown to be the allergen to which most sufferers are sensitive (Ogawa et al).

In order to address this, Herman et al  created a transgenic soybean line by using transgene-induced gene silencing, where a portion of the Gly m Bd 30K gene was introduced to the experimental plants. The resulting soybeans demonstrated complete suppression of the expression of Gly m Bd 30K with no other reported effects on plant growth or protein expression. This transgenic line should prove hypoallergenic for individuals sensitive only to the Gly m Bd 30K allergen, although full tests to confirm this have yet to be published.

It should be possible in the future to apply this gene silencing method to the natural mutant line in order to create a soybean lacking all three major allergens, leading to the development of highly hypoallergenic soybean products.

### Hypoallergenic soybeans demonstrate positive signs in early trials
A preliminary trial by Ogawa et al tested the allergenicity of an allergen-reduced variety of soybean product created by a combination of chemical breeding and chemical treatment, and the researchers found around 80% of soybean allergy patients could tolerate the product with no adverse effects.

**Sources**

NHS Choices website https://www.nhs.uk/

T Ogawa, M Samoto, K Takahashi "Soybean Allergens and Hypoallergenic Soybean Products" Journal of Nutritional Science and Vitaminology 46:271-279  

M Samota, Y Fukuda, K Takahashi "Substantially Complete Removal of Three Major Allergenic Soybean Proteins From Soy Protein By Using a Mutant Soybean, Tohoku 124" Bioscience, Biotechnology ad Biochemistry 61:2148-2150 

T Ogawa, N Bando, H Tsuji "Investigation of the IgE-Binding Proteins in Soybeans by Immunoblotting with the Sera of the Soybean-Sensitive Patients with Atopic Dermatitis" Journal of Nutritional Science and Vitaminology 37:555-565 

EM Herman, RM Helm, R Jung, AJ Kinney "Genetic Modification Removes and Immunodominant Allergen from Soybean" Plant Physiology 132:36-43

LS Jackson,MG Knize, JN Morgan “Impact of Processing on Food Safety” ISBN 0-306-46051-3