Lack of cross-reactivity between the Bacillus thuringiensis derived protein Cry1F in maize grain and dust mite Der p7 protein with human sera positive for Der p7-IgE (original) (raw)
Related papers
The novel proteins introduced into the genetically modified (GM) crops need to be evaluated for the potential allergenicity before their introduction into the food chain to address the safety concerns of consumers. At present, there is no single definitive test that can be relied upon to predict allergic response in humans to a new protein; hence a composite approach to allergic response prediction is described in this study. The present study reports on the evaluation of the Cry proteins, encoded by cry1Ac, cry1Ab, cry2Ab, cry1Ca, cry1Fa/cry1Ca hybrid, being expressed in Bt food crops that are under field trials in India, for potential allergenic cross-reactivity using bioinformatics search tools. The sequence identity of amino acids was analyzed using FASTA3 of AllergenOnline version 10.0 and BLASTX of NCBI Entrez to identify any potential sequence matches to allergen proteins. As a step further in the detection of allergens, an independent database of domains in the allergens available in the AllergenOnline database was also developed. The results indicated no significant alignment and similarity of Cry proteins at domain level with any of the known allergens revealing that there is no potential risk of allergenic cross-reactivity.
Bioinformatic Methods for Allergenicity Assessment Using a Comprehensive Allergen Database
International Archives of Allergy and Immunology, 2002
Background: A principal aim of the safety assessment of genetically modified crops is to prevent the introduction of known or clinically cross-reactive allergens. Current bioinformatic tools and a database of allergens and gliadins were tested for the ability to identify potential allergens by analyzing 6 Bacillus thuringiensis insecticidal proteins, 3 common non-allergenic food proteins and 50 randomly selected corn (Zea mays) proteins. Methods: Protein sequences were compared to allergens using the FASTA algorithm and by searching for matches of 6, 7 or 8 contiguous identical amino acids. Results: No significant sequence similarities or matches of 8 contiguous amino acids were found with the B. thuringiensis or food proteins. Surprisingly, 41 of 50 corn proteins matched at least one allergen with 6 contiguous identical amino acids. Only 7 of 50 corn proteins matched an allergen with 8 contiguous identical amino acids. When assessed for overall structural similarity to allergens, these 7 plus 2 additional corn proteins shared 635% identity in an overlap of 680 amino acids, but only 6 of the 7 were similar across the length of the protein, or shared 1 50% identity to an allergen. Conclusions: An evaluation of a protein by the FASTA algorithm is the most predictive of a clinically relevant cross-reactive allergen. An additional search for matches of 8 amino acids may provide an added margin of safety when assessing the potential allergenicity of a protein, but a search with a 6-amino-acid window produces many random, irrelevant matches.
No Adjuvant Effect of Bacillus thuringiensis-Maize on Allergic Responses in Mice
PLoS ONE
Genetically modified (GM) foods are evaluated carefully for their ability to induce allergic disease. However, few studies have tested the capacity of a GM food to act as an adjuvant, i.e. influencing allergic responses to other unrelated allergens at acute onset and in individuals with pre-existing allergy. We sought to evaluate the effect of short-term feeding of GM Bacillus thuringiensis (Bt)-maize (MON810) on the initiation and relapse of allergic asthma in mice. BALB/c mice were provided a diet containing 33% GM or non-GM maize for up to 34 days either before ovalbumin (OVA)-induced experimental allergic asthma or disease relapse in mice with pre-existing allergy. We observed that GM-maize feeding did not affect OVA-induced eosinophilic airway and lung inflammation, mucus hypersecretion or OVA-specific antibody production at initiation or relapse of allergic asthma. There was no adjuvant effect upon GM-maize consumption on the onset or severity of allergic responses in a mouse ...
Journal of AOAC International
Global commercial production of genetically modified (GM) crops has grown to over 67 million hectares annually, primarily of herbicide-tolerant and insect protection crop varieties. GM crops are produced by the insertion of specific genes that either encode a protein, or a regulatory RNA sequence. A comprehensive safety evaluation is conducted for each new commercial GM crop, including an assessment of the potential allergenicity of any newly introduced protein. If the gene was derived from an allergenic organism, or the protein sequence is highly similar to a known allergen, immunoassays, e.g., Western blot assays and enzyme-linked immunosorbent assay tests, are performed to identify protein-specific IgE binding by sera of individuals allergic to the gene source, or the source of the sequence-matched allergen. Although such assays are commonly used to identify previously unknown allergens, criteria have not been established to demonstrate that a protein is unlikely to cause allergi...
Clinical and Laboratory Investigation of Allergy to Genetically Modified Foods
Environmental Health Perspectives, 2002
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. Thus, the potential for occupational and consumer risks needs to be assessed.
PloS one, 2015
Genetically modified, (GM) crops with potential allergens must be evaluated for safety and endogenous IgE binding pattern compared to native variety, prior to market release. To compare endogenous IgE binding proteins of three GM maize seeds containing Cry 1Ab,1Ac,1C transgenic proteins with non GM maize. An integrated approach of in silico & in vitro methods was employed. Cry proteins were tested for presence of allergen sequence by FASTA in allergen databases. Biochemical assays for maize extracts were performed. Specific IgE (sIgE) and Immunoblot using food sensitized patients sera (n = 39) to non GM and GM maize antigens was performed. In silico approaches, confirmed for non sequence similarity of stated transgenic proteins in allergen databases. An insignificant (p> 0.05) variation in protein content between GM and non GM maize was observed. Simulated Gastric Fluid (SGF) revealed reduced number of stable protein fractions in GM then non GM maize which might be due to shift o...
Identification of the IgE-Binding Cross-Reacting Allergen Repertoir of dible Insects
2018
Allergic manifestations to the ingestion of edible insects have been reported, especially in countries where edible insects are traditionally consumed. However, to date, allergens of edible insects have been poorly investigated. The AllergenOnline server was used for assessing the allergenic character of the putative IgE-binding crossreactive allergens from the consumed yellow mealworm, silkworm, house fly maggot, migratory locust, house cricket, greater wax moth, black soldier fly, American grasshopper and Indian mealmoth. Positive hits correspond to allergens exhibiting >35% identity over an 80-residue sliding window and 100% identity over an 8-residue sliding window, respectively. Most of the hits consist of allergens from arthropods such as dust mites, crustaceans and insects, and more rarely, of allergens from mollusks, nematodes, and fungi. All the identified allergens share conserved amino acid sequences and three-dimensional structures. Accordingly, the allergens of edibl...
Gaining perspective on the allergenicity assessment of genetically modified food crops
Expert Review of Clinical …, 2005
Gene tic ally mo difie d p lant s ar e cr ea ted b y the ins er tio n of for eig n g enes int o pla nt c ells followed by the generation of reproductively stable stock plants for rapid and precise i m pr ov em en t s i n a gr i c u l tu r al c rop s. C u rr en t pr od u ct s p rov i d e r es i st an c e to i n se ct pe st s , pl a n t viruses or herbicides. Future products include nutritionally enhanced crops, salt and draught tolerant crops and plant produced industrial enzymes or pharmaceuticals. The risk that a newly expressed protein might cause serious allergic reactions is real, but the probability is r el a ti ve l y s m al l. Re gu l a to r y ag en c i es r eq u i re a pr em a rk et ev al u a ti on of th e ge n et i ca l ly m od i fi ed cr op to re du ce th e po ten ti al f or i n cr ea se d r i s ks of foo d a l l er gy. W h i l e a bs ol u t e p ro of of sa fe ty i s n ot pos s i bl e , th e m aj o r ri s k-t ra n sf er of a p ote n t m a j or a ll e rg en o r n ear l y i d en ti c al cr os s re act i ve p rot ei n-i s m i n i m i z ed by a l l er ge n-s pe ci fi c s er u m i m m u n og l obu li n E t es ts t h at ev al u a te pr ot ei n s t ak en f rom m ajo r al l er g en i c so u rc es or p ro te i n s w i t h s eq u en ce s h i gh l y similar to any allergen. Other tests are performed to identify proteins that are likely to sensitize consumers. Experience indicates the current assessment process is working eff ec ti ve l y. H ow eve r, fu r t h er gu i d an c e o n bi o i n for m at i cs an d i m m u n og l ob u l in E a ss ay s co u l d increase the reliability of the assessment. Further development of alternative assays may be n ee de d to as s es s th e n ex t g en e ra ti o n of p rod u ct s .
Analysis of Genetically Modified Maize Allergens by PCR
2022
Detection of genetically modified (GM) maize allergens is important for food safety assessment and labeling, health protection and consumer information. This study describes novel polymerase chain reaction (PCR) methods for analysis of GM maize allergens. The investigation was focused on the insect resistant GM maize event MON 810. The set of certified reference materials consisting of 0-5% MON810 were used for the optimization of the PCR systems. New oligonucleotide primers were designed for the genes of two important food allergens, such as maize Zea m 8 (chitinase) as well as GMO-specific Cry1Ab delta-endotoxin expressed in the insect resistant GMOs. The agarose gel electrophoresis revealed that PCR method using primers Zea8m130f/ Zea8m130r enables an effective analysis of maize allergen Zea m 8 whereas PCR method with primers Cry102f/Cry102f allows accurate detection of GMO allergen Cry1Ab delta-endotoxin. Moreover, this method may be applied for screening of insect-resistant GM...