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United States Department of Agriculture

Agricultural Research Service

Research Project: REDUCING THE ALLERGENIC PROPERTIES OF PEANUTS Project Number: 6435-43440-043-00
Project Type: Appropriated

Start Date: Dec 01, 2009
End Date: Sep 30, 2010

Objective:
1. Analyze the immunological and allergic properties of peanuts subjected to differing processing conditions, and identify the specific modified amino acids responsible for altered immunogenicity of the major allergens. 2. Develop processing technologies for producing hypoallergenic peanuts and or peanut products and test their allergenicity in vivo. 3. Clone, express, and purify the major peanut and select tree nut and legume allergens, and fragments thereof, in recombinant form to further delineate clinically-relevant antibody-allergen interactions. 4. Assess the role of processing-induced chemical or structural modifications on the individual allergens by systematically altering amino acids thought to be important in clinically-symptomatic allergic reactions. 5. Develop computer models and/or determine NMR/crystal structures of native and recombinant peanut and select tree nut and legume allergens in raw and processed forms. 6. Combine the structural information obtained with the empirical knowledge from Objectives 3, 4, and 5 to identify clinically-relevant allergen-antibody interactions in peanut and tree nut allergy. 7. Develop and improve immunoassays for detection of peanut, select tree nut and soy allergen residues before and after processing (i.e. roasting, baking into cookies, etc.) 8. After establishing standardized protocols for determining threshold doses for peanut, select tree nut, and soy allergens, determine threshold (minimal eliciting) dose of reactivity for processed forms of these allergens and develop computational and statistical models to estimate population thresholds.

Approach:
Peanuts, tree nuts, and legumes will be subjected to processing, and the allergens will be compared for changes in digestibility and antibody binding (IgE); structural alterations (e.g. changes in secondary structure, cross-linking); solubility and degradation; and functional properties (e.g. oligomerization, enzymatic ability). The prominent allergens from the selected nuts and legumes will be cloned, expressed, and purified and then subjected to specific chemical treatments that mimic reactions that occur during processing. Alterations to structure, function, and allergic properties will be assessed. Amino acid sequences thought to be modified during processing will be altered through specific reactions to confirm modification, and the structural properties will be assessed via circular dichrosim and molecular modeling methods. Protein homology models will be developed for the selected allergens from the different nuts and legumes, and used to determine particular structural or chemical changes empirically determined to alter IgE binding. The structure of small allergens, for which structural information is unavailable for homology modeling, will be subjected to nuclear magnetic resonance (NMR) to resolve their structure. Based on these protein models and empirical data, known functional foods, will be selected and assessed for interfering with antibody recognition of various allergens. Enzyme linked immunosorbent assays will be optimized for recognition of allergens in various food products and processing lines following different processes. To enable regulatory agencies to adopt proper labeling guidelines for manufacturers, threshold dose determination protocols will be developed for processed forms of peanut, tree nut, and soy allergens. Small-scale threshold dose studies will be carried out, and the results will be used to develop computational and statistical models to estimate population thresholds.

Last Modified: 10/21/2014
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