Antigenic determinants of asthma-associated allergens for design of immunotherapy

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DESCRIPTION (provided by applicant): Antigenic determinants of asthma-associated allergens for design of immunotherapy Project Summary/Abstract Allergic reactions to cockroach and dust mite are important health problems in the U.S. affecting up to 83% of asthmatic children in inner city areas and are a risk factor for emergency room admission with asthma. The main cockroach species in the U.S., Blattella germanica, produces Bla g 2 which induces sensitization at exposure levels 10-100 times lower than cat and mite allergens, and has the highest prevalence of sensitization among cockroach allergens (40-70%). Der p 1 and Der f 1 are cysteine proteases produced by the dust mites Dermatophagoides pteronyssinus and D. farinae, respectively. IgE sensitization to these Group 1 allergens is >80% among mite allergic patients. Proteolytic activity of Der p 1 may enhance IgE antibody production and contribute to lung inflammation in asthma but Bla g 2 is an inactive aspartic protease- homolog. The main goal of this project is to investigate the antigenic structure of proteolytic (mite Group 1) and non-proteolytic (Bla g 2) allergens associated with asthma. Allergens will be co-crystallized with monoclonal antibodies, and the key amino acids involved in antibody (IgE and mAb) binding will be identified. Alternatively, identification of IgE antibody binding epitopes will be performed by phage display technology. The specific aims are: 1) mapping of antigenic determinants in Bla g 2 by crystallography; 2) mapping of antigenic determinants of Group 1 mite allergens by crystallography and analysis of the structural basis for the cross-reactivity between Der p 1 and Der f 1; and 3) localization of the key amino acids involved in the antibody binding epitopes by site-directed mutagenesis studies and identification of hypoallergenic mutants with T cell reactivity that could be used for immunotherapy. IgE antibody binding to the epitope mutants will be analyzed by ELISA, multiplex array technology and cell mediator release assays. Mutants will be compared to select hypoallergenic forms for the design of vaccines for immunotherapy of mite and cockroach allergy. PUBLIC HEALTH RELEVANCE: Cockroach and mite allergy is associated with the development of asthma, which affects 17 million people in the U.S. The antigenic determinants of Bla g 2 and Group 1 mite allergens will be identified to elucidate the importance of the intrinsic properties of these allergens on allergic disease. Hypoallergenic mutants will be produced and tested for IgE antibody binding and T cell proliferation, and the information obtained will facilitate a rational design of allergy vaccines.