Box 3.1. Case study of Brazil nut protein gene expressed in soybean

Soybeans are deficient in essential sulfur-containing amino acids such as methionine and Brazil nuts are rich in this substance. A gene encoding a Brazil nut methionine-rich seed storage protein was introduced into soybean, in an experimental approach to develop improved animal feed. Brazil nuts are known to be allergenic, raising concern as to whether the product of the transferred gene would increase the allergenic potential of the soybean. Because the protein is from a known allergenic source, serological evaluation of the protein was performed. In this case, pooled serum from nine Brazil nut-sensitive individuals recognized the novel protein in soybean. Skin prick tests with three of these individuals confirmed the presence of the allergen in soybean. Based on these findings, further product development was discontinued, in case the improved animal feed inadvertently entered the human food chain.

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