Agbiotechnology and allergy - the status of the science

Assessing genetically modified crops to minimize the risk of increased food allergy: a review.
Goodman RE, Hefle SL, Taylor SL, van Ree R.

Food Allergy Research and Resource Program, University of Nebraska, Lincoln, NE
68583-0955, USA. rgoodman2@unlnotes.unl.edu

The first genetically modified (GM) crops approved for food use (tomato and soybean) were evaluated for safety by the United States Food and Drug Administration prior to commercial production. Among other factors, those products and all additional GM crops that have been grown commercially have been evaluated for potential increases in allergenic properties using methods that are consistent with the current understanding of food allergens and knowledge regarding the prediction of allergenic activity. Although there have been refinements, the key aspects of the evaluation have not changed. The allergenic properties of the gene donor and the host (recipient) organisms are considered in determining the appropriate testing strategy. The amino acid sequence of the encoded protein is compared to all known allergens to determine whether the protein is a known allergen or is sufficiently similar to any known allergen to indicate an increased probability of allergic cross-reactivity. Stability of the protein in the presence of acid with the stomach protease pepsin is tested as a risk factor for food allergenicity. In vitro or in vivo human IgE binding are tested when appropriate, if the gene donor is an allergen or the sequence of the protein is similar to an allergen. Serum donors and skin test subjects are selected based on their proven allergic responses to the gene donor or to material containing the allergen that was matched in sequence. While some scientists and regulators have suggested using animal models, performing broadly targeted serum IgE testing or extensive pre- or post-market clinical tests, current evidence does not support these tests as being predictive or practical. Based on the evidence to date, the current assessment process has worked well to prevent the unintended introduction of allergens in commercial GM crops.

Int Arch Allergy Immunol. 2005 Jun;137(2):153-66. Epub 2005 Jun 8.
Comment in:
Int Arch Allergy Immunol. 2005 Jun;137(2):151-2.

Allergenicity assessment of genetically modified crops--what makes sense?
Goodman RE, Vieths S, Sampson HA, Hill D, Ebisawa M, Taylor SL, van Ree R.
Department of Food Science & Technology, University of Nebraska, Lincoln,
Nebraska, 68583-0955, USA. rgoodman2@unlnotes.unl.edu

GM crops have great potential to improve food quality, increase harvest yields and decrease dependency on certain chemical pesticides. Before entering the market their safety needs to be scrutinized. This includes a detailed analysis of allergenic risks, as the safety of allergic consumers has high priority. However, not all tests currently being applied to assessing allergenicity have a sound scientific basis. Recent events with transgenic crops reveal the fallacy of applying such tests to GM crops.

Nat Biotechnol. 2008 Jan;26(1):73-81.
Erratum in:
Nat Biotechnol. 2008 Feb;26(2):241.

Key quote from Goodman et al. 2008

Although there are not yet any publications reporting validation of the approach using 35% homology over an 80-amino-acid window (or more than 50% overall homology) to predict likely cross-reactivity, it is clear that it is an improvement over methods using sequence homology over 6 or 8 amino acids11. These short peptide matches have not been validated as predictive tools and should be rejected on the basis of extremely high numbers of false-positive hits11–14. The eight-amino-acid match was originally selected without evidence of predictability based on the idea that it would represent both a theoretical B-cell epitope as well as a minimum size for a conserved T-cell epitope5. Stadler and Stadler 13 [Abstract below)] reported that a 6-mer match resulted in more than two-thirds of all proteins in Swiss-Prot being predicted to be allergens, and more than 40% of the human genome being predicted as such. Obviously, the use of short amino matching searches (6–8 mer) is not a useful approach for allergenicity assessment, but it has never been truly renounced. Consequently, a few regulatory authorities sometimes still require bioinformatics analyses based on 6-mer matches (Box 3).
Ref 11. Goodman, R.E. & Wise, J. Predicting the allergenicity of novel proteins in genetically modified organisms. in Food Allergy (eds. Maleki S.J. et al.) 219–247 (American Society of Microbiology Press, Washington, DC, 2006).
Ref 12. Hileman, R.E. et al. Bioinformatic methods for allergenicity assessment using a comprehensive allergen database. Int. Arch. Allergy Immunol. 128, 280–291 (2002).
Ref 13. Stadler, M.B. & Stadler, B.M. Allergenicity prediction by protein sequence. FASEB J. 17, 1141–1143 (2003).
Ref 14. Silvanovich, A. et al. The value of short amino acid sequence matches for prediction of protein allergenicity. Toxicol. Sci. 90, 252–258 (2006)

Allergenicity prediction by protein sequence.
FASEB J. 2003 Jun;17(9):1141-3. Epub 2003 Apr 22.
Stadler MB, Stadler BM.
Institute of Immunology, University of Bern, Sahlihaus 2, Inselspital, CH-3010
Bern, Switzerland. michael.stadler@insel.ch

Potential allergenicity of transgenic proteins for consumption must be investigated before their introduction into the food chain. A prerequisite is sequence analysis. We have critically reviewed the performance of the current guidelines proposed by the Food and Agriculture Organization (FAO) and the World Health Organization (WHO) for allergenicity prediction based on protein sequence and show that its precision is very low. To improve prediction, we propose a new strategy based on sequence motifs identified from a new allergen database. If tested on random test sequences and known allergens, both methods are apparently very sensitive. However, the precision of our motif-based prediction (95.5%) is superior to the current method (36.6%). We conclude that the proposed motif-based prediction is a superior alternative to the current method for use in the decision-tree approach for allergenicity assessment.

Review article
Risks of allergic reactions to biotech proteins in foods: perception and reality
Allergy Volume 60 Issue 5, Pages 559 - 564 (2005)
S. B. Lehrer , G. A. Bannon

1 Section of Clinical Immunology, Allergy and Rheumatology, Tulane University School of Medicine, New Orleans, LA ; 2 Product Characterization Center, The Monsanto Company, St Louis, MO, USA

In recent years, significant attention has been paid to the use of biotechnology to improve the quality and quantity of the food supply due in part to the projected growth in the world population, plus limited options available for increasing the amount of land under cultivation. Alterations in the food supply induced by classical breeding and selection methods typically involve the movement of large portions of genomic DNA between different plant varieties to obtain the desired trait. This is in contrast to techniques of genetic engineering which allows the selection and transfers specific genes from one species to another. The primary allergy risk to consumers from genetically modified crops may be placed into one of three categories. The first represents the highest risk to the allergic consumer is the transfer of known allergen or cross-reacting allergen into a food crop. The second category, representing an intermediate risk to the consumer, is the potential for replacing the endogenous allergenicity of a genetically-modified crop. The last category involves expression of novel proteins that may become allergens in man and generally represents a relatively low risk to the consumer, although this possibility has received attention of late. In order to mitigate the three categories of potential allergy risk associated with biotech 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 result of this risk assessment process to date is that no biotech proteins in foods have been documented to cause allergic reactions. These results indicate that the current assessment process is robust, although as science of allergy and allergens evolves, new information and new technology should help further the assessment process for potential allergenicity.

allergy • benefits • genetically modified foods • risks

Food biotechnology: is this good or bad? Implications to allergic diseases.
Ann Allergy Asthma Immunol. 2003 Jun;90(6 Suppl 3):90-8.
Helm RM.
Arkansas Children's Hospital Research Institute, Little Rock, Arkansas
72202-3591, USA. helmrick@uams.edu

BACKGROUND: Food biotechnology represents advancement in the traditional interspecies and intergeneric breeding methods for improving food supplies worldwide. With respect to safety, foods developed through biotechnology techniques represent one of the most extensively reviewed agricultural advancements in history.
OBJECTIVE: To review the relevant issues with respect to foods from genetically modified crops and allergenicity.
DATA SOURCES: To impart this information, the author will rely upon his experiences with investigations into food allergy and food allergens, participation in various workshops designed to determine allergenicity of novel proteins introduced into the diet, web sites, issue papers, and articles relevant to the topic.
RESULTS: Given that there are no validated methods or models to determine potential allergenicity of novel proteins, criteria have been established based upon characteristics of known food allergens. The combination of genetic and bioinformatics information available from known food allergens applied to foods developed from genetically modified crops to avoid the inadvertent introduction of allergens into foods should pose no significant allergenic concern to individuals with a genetic predisposition to food allergy. Education and sound scientific evaluation provided to the consumer should alleviate any fear of emotionalism as implied by "Frankenfoods."
CONCLUSIONS: The estimation that more than two trillion transgenic plants have been grown in 1999 and 2000 alone, with no overt documented adverse food reactions being reported, indicates that genetic modification through biotechnology will not impose immediate significant risks as food allergen sources beyond that of our daily dietary intake of foods from crop plants.

Benefits and concerns associated with biotechnology-derived foods: can additional research reduce children health risks?
Eur Rev Med Pharmacol Sci. 2006 Jul-Aug;10(4):197-206.
Cantani A.

Allergy and Clinical Immunology Division, Pediatric Department, La Sapienza
University, Rome, Italy.

The development of techniques devised for the genetic manipulation of foods poses new risks for children with food allergy (FA). The introduction of foreign allergenic proteins from different foods into previously tolerated foods may trigger allergic reactions, often complicating with anaphylactic shock in a subset of allergic babies. Children with FA, even if subjected to preventative diets, always challenge the risk of developing allergic manifestations after unintentional intake of a non tolerated food in restaurant settings, with relatives or schoolmates, etc, where product labelling is necessarily lacking.
The introduction of potentially allergenic proteins into foods generally considered safe for allergic children can be done deliberately, by either substantially altering the food ingredients, or by genetic manipulation which change the composition or transfer allergens, or unintentionally by quality-control failures, due to contaminations in the production process, or to genetic mismanipulation. There is a controversy between multinationals often favored by governments and consumer association resistance, thus an equidistant analysis poses some unprecedented impediments. The importance of FA and the potential of transgenic plants to bring food allergens into the food supply should not be disregarded. The expression in soybeans of a Brazil nut protein resulted in a food allergen expressed in widely used infant formulas, so paving the way to an often reported multinational debacle. Genetic engineering poses innovative ethical and social concerns, as well as serious challenges to the environment, human health, animal welfare, and the future of agriculture. In this paper will be emphasized practical concepts more crucial for pediatricians.

Allergen motifs and the prediction of allergenicity.
Immunol Lett. 2007 Mar 15;109(1):47-55. Epub 2007 Jan 30.
Marti P, Truffer R, Stadler MB, Keller-Gautschi E, Crameri R, Mari A, Schmid-Grendelmeier P, Miescher SM, Stadler BM, Vogel M.

Institute of Immunology, Inselspital, 3010 Bern, Switzerland.

We have recently shown that the majority of allergens can be represented by allergen motifs. This observation prompted us to experimentally investigate the synthesized peptides corresponding to the in silico motifs with regard to potential IgE binding and cross-reactions with allergens. Two motifs were selected as examples to conduct in vitro studies. From the first motif, derived from allergenic MnSOD sequences, the motif stretch of the allergen Asp f 6 was selected and synthesized as a peptide (MnSOD Mot). The corresponding full-length MnSOD was also expressed in Escherichia coli and both were compared for IgE reactivity with sera of patients reacting to the MnSOD of Aspergillus fumigatus or Malassezia sympodialis. For the second motif, the invertebrate tropomyosin sequences were aligned and a motif consensus sequence was expressed as a recombinant protein (Trop Mot). The IgE reactivity of Trop Mot was analyzed in ELISA and compared to that of recombinant tropomyosin from the shrimp Penaeus aztecus (rPen a 1) in ImmunoCAP. MnSOD Mot was weakly recognized by some of the tested sera, suggesting that the IgE binding epitopes of a multimeric globular protein such as MnSOD cannot be fully represented by a motif peptide. In contrast, the motif Trop Mot showed the same IgE reactivity as shrimp full-length tropomyosin, indicating that the major allergenic reactivity of a repetitive structure such as tropomyosin can be covered by a motif peptide. Our results suggest that the motif-generating algorithm may be used for identifying major IgE binding structures of coiled-coil proteins.

Clinical and laboratory investigation of allergy to genetically modified foods.
Environ Health Perspect. 2003 Jun;111(8):1114-21.
Bernstein JA, Bernstein IL, Bucchini L, Goldman LR, Hamilton RG, Lehrer S, Rubin C, Sampson HA.
Department of Medicine, University of Cincinnati, Cincinnati, Ohio, USA.

Technology has improved the food supply since the first cultivation of crops. Genetic engineering facilitates the transfer of genes among organisms. Generally, only minute amounts of a specific protein need to be expressed to obtain the desired trait. Food allergy affects only individuals with an abnormal immunologic response to food--6% of children and 1.5-2% of adults in the United States. Not all diseases caused by food allergy are mediated by IgE. A number of expert committees have advised the U.S. government and international organizations on risk assessment for allergenicity of food proteins. These committees have created decision trees largely based on assessment of IgE-mediated food allergenicity. Difficulties include the limited availability of allergen-specific IgE antisera from allergic persons as validated source material, the utility of specific IgE assays, limited characterization of food proteins, cross-reactivity between food and other allergens, and modifications of food proteins by processing. StarLink was a corn variety modified to produce a Bacillus thuringiensis (Bt) endotoxin, Cry9C. The Centers for Disease Control and Prevention investigated 51 reports of possible adverse reactions to corn that occurred after the announcement that StarLink, allowed for animal feed, was found in the human food supply. Allergic reactions were not confirmed, but tools for postmarket
assessment were limited. Workers in agricultural and food preparation facilities have potential inhalation exposure to plant dusts and flours. In 1999, researchers found that migrant health workers can become sensitized to certain Bt spore extracts after exposure to Bt spraying.

See earlier GMO Pundit post One dog good, two dogs even better.