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      Suggested Improvements for the Allergenicity Assessment of Genetically Modified Plants Used in Foods

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          Abstract

          Genetically modified (GM) plants are increasingly used for food production and industrial applications. As the global population has surpassed 7 billion and per capita consumption rises, food production is challenged by loss of arable land, changing weather patterns, and evolving plant pests and disease. Previous gains in quantity and quality relied on natural or artificial breeding, random mutagenesis, increased pesticide and fertilizer use, and improved farming techniques, all without a formal safety evaluation. However, the direct introduction of novel genes raised questions regarding safety that are being addressed by an evaluation process that considers potential increases in the allergenicity, toxicity, and nutrient availability of foods derived from the GM plants. Opinions vary regarding the adequacy of the assessment, but there is no documented proof of an adverse effect resulting from foods produced from GM plants. This review and opinion discusses current practices and new regulatory demands related to food safety.

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          Most cited references39

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          Epidemiology of food allergy.

          Adverse reactions to foods can occur for a variety of reasons, but a food allergy is caused by a specific immune response. Challenges to determine the prevalence of food allergy include misclassification, biased participation, lack of simple diagnostic tests, rapid evolution of disease, large numbers of potential triggers, and varied clinical phenotypes. Nonetheless, it is clear that this is a common disorder, with studies suggesting a cumulative prevalence of 3% to 6%, representing a significant impact on quality of life and costs. The inclusion of mild reactions to fruits and vegetables could result in calculation of prevalence exceeding 10% in some regions. There are data from numerous studies to suggest an increase in prevalence, but methodologic concerns warrant caution. Prevalence varies by age, geographic location, and possibly race/ethnicity. Many childhood food allergies resolve. Population-based epidemiologic studies have generated numerous novel theories regarding risks, including modifiable factors such as components of the maternal and infant diet, obesity, and the timing of food introduction. Recent and ongoing studies provide insights on risk factors, prevalence, and natural course that may inform clinical trials to improve diagnosis, prevention, and treatment. Copyright © 2011 American Academy of Allergy, Asthma & Immunology. Published by Mosby, Inc. All rights reserved.
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            Structural biology of allergens.

            R Aalberse (2000)
            One of the major challenges of molecular allergy is to predict the allergenic potential of a protein, particularly in novel foods. Two aspects have to be distinguished: immunogenicity and cross-reactivity. Immunogenicity reflects the potential of a protein to induce IgE antibodies, whereas cross-reactivity is the reactivity of (usually preexisting) IgE antibodies with the target protein. In addition to these two issues, the relation between IgE-binding potential and clinical symptoms is of interest. This is influenced by physical properties (eg, stability and size) and immunologic properties (affinity and epitope valence). Discussions on immunogenicity and cross-reactivity of allergens rely on the establishment of structural similarities and differences among allergens and between allergens and nonallergens. For comparisons between the 3-dimensional protein folds, the representation as 2-dimensional proximity plots provides a convenient visual aid. Analysis of approximately 40 allergenic proteins (or parts of these proteins), of which the protein folds are either known or can be predicted on the basis of homology, indicates that most of these can be classified into 4 structural families: (1) antiparallel beta-strands: the immunoglobulin-fold family (grass group 2, mite group 2), serine proteases (mite group 3, 6, and 9), and soybean-type trypsin inhibitor (Ole e 1, grass group 11); (2) antiparallel beta-sheets intimately associated with one or more alpha-helices: tree group 1, lipocalin, profilin, aspartate protease (cockroach group 2); (3) (alpha+beta) structures, in which the alpha- and beta-structural elements are not intimately associated: mite group 1, lysozyme/lactalbumin, vespid group 5; and (4) alpha-helical: nonspecific lipid transfer protein, seed 2S protein, insect hemoglobin, fish parvalbumin, pollen calmodulin, mellitin from bee venom, Fel d 1 chain 1, serum albumin. Allergens with parallel beta-strands (in combination with an alpha-helix linking the two strands, a motif commonly found in, for example, nucleotide-binding proteins) seem to be underrepresented. The conclusion is that allergens have no characteristic structural features other than that they need to be able to reach (and stimulate) immune cells and mast cells. Within this constraint, any antigen may be allergenic, particularly if it avoids activation of T(H)2-suppressive mechanisms (CD8 cells and T(H)1 cells).
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              Safety and advantages of Bacillus thuringiensis-protected plants to control insect pests.

              Plants modified to express insecticidal proteins from Bacillus thuringiensis (referred to as Bt-protected plants) provide a safe and highly effective method of insect control. Bt-protected corn, cotton, and potato were introduced into the United States in 1995/1996 and grown on a total of approximately 10 million acres in 1997, 20 million acres in 1998, and 29 million acres globally in 1999. The extremely rapid adoption of these Bt-protected crops demonstrates the outstanding grower satisfaction of the performance and value of these products. These crops provide highly effective control of major insect pests such as the European corn borer, southwestern corn borer, tobacco budworm, cotton bollworm, pink bollworm, and Colorado potato beetle and reduce reliance on conventional chemical pesticides. They have provided notably higher yields in cotton and corn. The estimated total net savings to the grower using Bt-protected cotton in the United States was approximately $92 million in 1998. Other benefits of these crops include reduced levels of the fungal toxin fumonisin in corn and the opportunity for supplemental pest control by beneficial insects due to the reduced use of broad-spectrum insecticides. Insect resistance management plans are being implemented to ensure the prolonged effectiveness of these products. Extensive testing of Bt-protected crops has been conducted which establishes the safety of these products to humans, animals, and the environment. Acute, subchronic, and chronic toxicology studies conducted over the past 40 years establish the safety of the microbial Bt products, including their expressed insecticidal (Cry) proteins, which are fully approved for marketing. Mammalian toxicology and digestive fate studies, which have been conducted with the proteins produced in the currently approved Bt-protected plant products, have confirmed that these Cry proteins are nontoxic to humans and pose no significant concern for allergenicity. Food and feed derived from Bt-protected crops which have been fully approved by regulatory agencies have been shown to be substantially equivalent to the food and feed derived from conventional crops. Nontarget organisms exposed to high levels of Cry protein are virtually unaffected, except for certain insects that are closely related to the target pests. Because the Cry protein is contained within the plant (in microgram quantities), the potential for exposure to farm workers and nontarget organisms is extremely low. The Cry proteins produced in Bt-protected crops have been shown to rapidly degrade when crop residue is incorporated into the soil. Thus the environmental impact of these crops is negligible. The human and environmental safety of Bt-protected crops is further supported by the long history of safe use for Bt microbial pesticides around the world. Copyright 2000 Academic Press.
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                Author and article information

                Contributors
                rgoodman2@unl.edu
                okobea@huskers.unl.edu
                Journal
                Curr Allergy Asthma Rep
                Current Allergy and Asthma Reports
                Current Science Inc. (New York )
                1529-7322
                1534-6315
                13 April 2011
                13 April 2011
                August 2011
                : 11
                : 4
                : 317-324
                Affiliations
                Food Allergy Research and Resource Program, University of Nebraska, 143 Food Industry Complex, Lincoln, NE 68583–0955 USA
                Article
                195
                10.1007/s11882-011-0195-6
                3130127
                21487714
                e85f78f1-d24d-4c0b-b307-e5146a38c4cd
                © The Author(s) 2011
                History
                Categories
                Article
                Custom metadata
                © Springer Science+Business Media, LLC 2011

                Immunology
                genetically modified,risk assessment,ige,allergenicity,improvement,food safety,plants
                Immunology
                genetically modified, risk assessment, ige, allergenicity, improvement, food safety, plants

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