Engineered hypo-allergens for specific immunotherapy for food allergy

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Food allergy is a major health concern in both children and adults. Food-hypersensitivity reactions affect about 8% of children and 3 % of adults. Hen egg white is one of the most common sources of allergic reactions, mainly in children. Approximately, two-thirds of children diagnosed with food allergies are reactive to egg white. Our previous work has been clearly identified ovalbumin (OA) and ovomucoid (OVM) as major egg white allergens. Furthermore, we have completed detailed B-cell and T-cell epitope mapping of both allergens and identified critical amino acids that affect IgE binding activity. This information will enable us to design specific hypo-allergens for immunotherapy. The hypothesis is that specifically designed recombinant OA and OVM allergens or peptides that lack of IgE-epitopes (low allergenicity), but show good T-cell antigenecity (retain T-cell epitopes) could induce tolerance to egg allergens which represent an attractive solution to prevent and treat egg allergy. This could result in specific T-cell tolerance or anergy against the antigens. Modification of allergens will be performed by two different approaches, 1) recombinant hybrid peptides comprising OA or OVM MHC class II-restricted T-cell epitopes with E. coli expression system, and 2) site-directed mutagenesis altering dominant B-cell epitope structure or tertiary structure of the proteins. Hypo-sensitization and therapeutic tolerance of egg allergy will be evaluated using experimentally-induced allergy mice (BALB/c) by means of intraperitoneal of antigens. Analysis of Th1/Th2 and T-regulatory cells-associated cytokines (IFN-gamma, IL-4, IL-10, IL-12 and TGF-beta), specific antibodies (IgE, IgG1, IgG2a and IgG4) and histamine levels will be analyzed by enzyme-linked immunosorbent assay (ELISA) (splenocytes and sera) or real-time RT-PCR technique (mucosal immunity). The significance of the proposed project are 1) to direct us to develop hypo-food allergens or peptide-based immunotherapy for food allergic diseases, 2) better understanding mechanism of recombinant hypoallergen-induced immunotorelance, 3) to facilitate training of highly qualified personnel in food biotechnology/immunology/food safety area.