Identification of Two Linear IgE-Binding Epitopes of Artemisia Annua Major Allergen, Art an 3

Abstract

Background: Artemisia annua (A. annua) is a traditional herb native to Asia which has great therapeutic value. However, it’s the most common aeroallergen in autumn responsible for seasonal allergic rhinitis in northern China. Art an 3 is a major allergen of A. annua pollen, it belongs to the non-specific plant lipid-transfer protein (nsLTP) family and its immunoglobulin E (IgE)-binding epitope has not been reported. This study aims to identify the linear IgE-binding epitopes of Art an 3. Methods: Recombinant Art an 3 protein was prepared and its allergenicity was confirmed by Western blot assay. Overlapping peptides covering full-length Art an 3 protein were synthesized and the linear IgE binding epitopes of Art an 3 were characterized by dot-blot assay. The specific immunoglobulin G (IgG) antibody levels induced by immunizing the mice with carrier-coupled Art an 3 peptides were measured by enzyme-linked immunosorbent assay (ELISA). The inhibition of human IgE binding to rArt an 3 by peptide-specific mouse antibodies was analyzed by ELISA competition assay. Art an 3 homology model was built based on the Art v 3 crystal structure. Results: The recombinant Art an 3 has been prepared and two linear IgE-binding epitopes of Art an 3 were characterized. When coupled to a carrier protein and immunized mice, both of the epitope peptides induced Art an 3-specific IgG antibody, which could inhibit Artemisia allergic patients’ serum IgE binding to Art an 3. The IgE-binding epitopes were well-exposed on the protein surface. Conclusions: Two linear IgE-binding epitopes of Art an 3 were identified, and antisera raised from carrier-bound epitope peptides could inhibit patients’ IgE binding to Art an 3.