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ARS Home » Southeast Area » New Orleans, Louisiana » Southern Regional Research Center » Food Processing and Sensory Quality Research » Research » Research Project #438601

Research Project: Reducing the Development and Severity of Allergy to Peanuts and Tree Nuts

Location: Food Processing and Sensory Quality Research

Project Number: 6054-43440-052-00-D
Project Type: In-House Appropriated

Start Date: Jul 7, 2020
End Date: Jul 6, 2025

Objective:
Objective 1: Decipher the molecular, structural and immunological properties of purified native and recombinant allergens that contribute to allergenic potency towards development of therapeutic products. [NP306, C1, PS1C] Objective 2: Use serum from verified nut allergic and non-allergic individuals to identify and compare IgE and IgG binding sites (or epitopes) of known nut allergens with peptide microarrays to understand cross-reactivity between multiple allergens and improve diagnosis of nut allergy. [NP306, C1, PS1A] Objective 3: Characterize, quantify and monitor allergen characteristics and levels pre- and post-harvest, and pre- and post-processing of commercial nuts and nut-containing foods, and during nut seed development to produce hypoallergenic, prophylactic or therapeutic food products. [NP306, C1, PS1B] The immunoglobulin E (IgE) binding sites (epitopes) that are responsible for the symptoms of allergic disease and cross-reactivity among peanut, tree nut and pollen allergens will be identified with peptide microarray technology. The IgE and immunoglobulin G4 (IgG4, thought to act as an IgE-blocking antibody) epitopes will be identified for the most potent nut allergens. These will be modeled on the surface of allergen structures to identify location and common or cross-reactive (or potentially blocked) sequences and structures of allergens among nuts and pollens. Simultaneously, the changes in peanut and tree nut extracts or purified allergens thereof (recombinant or native) will be assessed before and after processing treatments for changes in allergenic properties. Proteins found to be immunologically altered by processing will be assessed within a total nut extract or they will be purified and analyzed for alterations in size, structure, digestibility, binding to various serum IgE and allergen-specific antibodies. The specific amino acid residues, or peptides thought to be modified during different processing events, and thought to contribute to altered allergenic properties, will be identified by mass spectrometry. The studies above will be combined to identify the influence of the processing-induced alteration in relationship to the immunoglobulin binding sites of nut allergens. This will guide the development of better diagnostics and therapeutics as well as processing technologies to reduce allergenicity of nuts and products thereof. Early intervention methods to reduce the allergenic potential of nuts, the natural variation in allergen gene sequence, expression, post-translational modification, stability and accumulation patterns in a model tree nut (pecan) will be studied. Less allergenic variants and factors that can be used to interfere with allergen accumulation in plants will also be characterized in detail. Collectively our studies will also contribute to the development of better detection tools and labeling practices for industry and regulatory agencies resulting in better protection of consumers.

Approach:
The immunoglobulin E (IgE) binding sites (epitopes) that are responsible for the symptoms of allergic disease and cross-reactivity among peanut, tree nut and pollen allergens will be identified with peptide microarray technology. The IgE and immunoglobulin G4 (IgG4, thought to act as an IgE-blocking antibody) epitopes will be identified for the most potent nut allergens. These will be modeled on the surface of allergen structures to identify location and common or cross-reactive (or potentially blocked) sequences and structures of allergens among nuts and pollens. Simultaneously, the changes in peanut and tree nut extracts or purified allergens thereof (recombinant or native) will be assessed before and after processing treatments for changes in allergenic properties. Proteins found to be immunologically altered by processing will be assessed within a total nut extract or they will be purified and analyzed for alterations in size, structure, digestibility, binding to various serum IgE and allergen-specific antibodies. The specific amino acid residues, or peptides thought to be modified during different processing events, and thought to contribute to altered allergenic properties, will be identified by mass spectrometry. The studies above will be combined to identify the influence of the processing-induced alteration in relationship to the immunoglobulin binding sites of nut allergens. This will guide the development of better diagnostics and therapeutics as well as processing technologies to reduce allergenicity of nuts and products thereof. Early intervention methods to reduce the allergenic potential of nuts, the natural variation in allergen gene sequence, expression, post-translational modification, stability and accumulation patterns in a model tree nut (pecan) will be studied. Less allergenic variants and factors that can be used to interfere with allergen accumulation in plants will also be characterized in detail. Collectively our studies will also contribute to the development of better detection tools and labeling practices for industry and regulatory agencies resulting in better protection of consumers.