Engineering, characterization and evaluation of hypoallergencic derivates of the major timothy grass pollen allergen, Phl p1, for specific immunotherapy

Type 1 allergy is a genetically determined immunodisorder with increasing prevalence, which is characterized by the production of IgE antibodies against per se harmless poteins ( i.e. allergens). Approximately 400 million allergic patients display symptoms to the major timothy grass pollen allergen Phl p 1, which is present in all grass species and belongs to the most potent elicitors of type 1 allergic symptoms worldwide. The most effective treatment against type 1 allergy to date is allergen specific immunotherapy, although the use of crude allergen extracts, consisting of mixtures of several allergens and non-allergenic components and the occurence of anaphylactic side effects cause unpredictable effects and failure of immunotherapy. In the last few years, it has however been demonstrated for several allergens that safety and efficacy of allergen specific immunotherapy can be improved by genetic engineering of hypoallergenic allergen derivatives i.e. allergen variants with reduced IgE reactivity. The aim of this project is the construction of a hypoallergenic Phl p 1 derivative for safe and improved immunotherapy. Based on structural and immunological information we plan to engineer a Phl p 1 variant with disrupted three-dimensional structure and thus reduced IgE reactivity. The hypoallergenic features of the engineered molecule will be evaluated in vitro and in vivo as well as in animal models. Ultimately, the hypoallergenic derivative will be tested in clinical immunotherapy studies. The proposed work is based on previously elaborated own data, comprising the determination of the three-dimensional structure of Phl p 1 by X- ray crystallography and the characterization of its IgE reactive moieties (i.e. epitopes). The superposition of the IgE epitopes onto the three-dimensional structure thus provided the knowledge of the spatial distribution of its IgE reactive moieties.