Amino Acid Substitution in Par j 2 Recombinant Allergen and Its Effect on IgE Binding Capacity

Therapeutic attempts to cure allergic diseases reduce symptoms without circumventing the onset of the allergic reaction. Specific immunotherapy (SIT), is the most commonly used treatment. Nevertheless, SIT may account for various adverse events. Therefore, different therapies have been developed in order to treat and prevent allergic reactions. Among these therapies, there is an increased interest in studying recombinant peptides mutated in the IgE binding site. Several studies have shown two major allergens of Parietaria judaica (Pj) named Par j 1 and Par j 2, which have been cloned and characterized by us. In our study we have fragmented the Par j 2 protein in order to determine the major epitopes recognized by human IgE and we used site-directed mutagenesis to identify potential amino acid residues involved in IgE binding. The IgE binding activity of the recombinant peptides was tested and the results showed that site-specific mutagenesis at positions K41, T42, T43, and C52 caused a loss of IgE binding. The goal of this work is to synthesize molecules which can induce a protective immune response against Pj. These molecules will be used in immunotherapy in order to create new vaccines for the treatment of Parietaria pollen allergy.