Sustainable Agriculture Literature Review - Boulder County

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nutritional quality of transgenic soybeans 805 or the codfish allergy in potatoes that have
been genetically engineered with cod protein genes to make the potatoes tolerate cold
storage. 806 In both of these cases, production of the GE foods was stopped and the
product was not allowed to go to market.
It becomes increasingly difficult to assess the allergenicity of GE foods when the gene is
transferred from a plant whose allergenic potential is unknown. As a result of this gene
transfer or vector insertion, it is possible that a new allergen is developed or the
expression level of a minor allergen is increased in the GE crop. Unfortunately, while
there are good animal models for nutritional and toxicological testing, no satisfactory
animal models have so far been developed for allergenicity testing. 807 For the time being,
only indirect methods are available for the assessment of the allergenic potential of GE
foods derived from sources of unknown allergenicity. 808 The World Health Organization
and the Food and Agriculture Organization of the United Nations’ report, Evaluation of
Allergenicity of Genetically Modified Foods, identified the need for further development
and validation of suitable animal models and procedures for the assessment of
allergenicity of foods derived from biotechnology. 809
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A study looking at the transfer of a gene from a kidney bean to field peas, to make the
peas resistant to bruchid storage beetles, demonstrated that the transgenic expression
leads to the synthesis of a modified form of protein that altered antigenic properties and
elicited an immune response from the tested mice. This means that the transgenic
protein altered immune response in the mice, but did not necessarily demonstrate
allergenicity. Based on these findings the authors concluded that the transgenic
expression of non-native proteins in plants may lead to the synthesis of structural
variants with altered immunogenicity. 810 This study caused a lot of media attention due to
the potential for GE crops to pose an allergy risk, though a number of other studies have
called into question the study’s design. 811, 812 Of concern is the model used to test for
allergenicity, which has not been widely used or tested and thus may not prove to be as
accurate as other methods. 813 Despite some questions about the accuracy of the study’s
design, the safety concerns raised by the study’s authors were enough to halt further
development of the transgenic variety and keep it from reaching the market. 814
In order to mitigate the three categories of potential allergy risk associated with GE
crops, all genes introduced into food crops undergo a series of tests designed to
determine if the biotech protein exhibits properties of known food allergens. The process
for assessing potential allergenicity was first proposed by the United States Department
of Agriculture (USDA) and later modified by the Food and Agriculture Organization and
the World Health Organization. The process begins by examining the source of the
gene. If it comes from a crop that contains a known allergen, both in vitro and in vivo
diagnostic tests may be required, depending on whether or not a gene is to be
introduced to a commodity crop. If the gene is not derived from a known allergen, the
amino acid sequence is examined for homologies that would indicate the potential to
bind immunoglobulin E. Furthermore, the amino acid sequence of all introduced genes,
whether derived from a known allergen or not, are compared to amino acid sequences of
conventional crops to determine the existence of other potential safety issues.
Allergenicity is further evaluated by determining a protein’s ability to withstand digestion
by pepsin using simulated gastric fluid. 815
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