Identification of a Sequential B-Cell Epitope on Major Allergen (Cry j 1) of Japanese Cedar (Cryptomeria japonica) Pollen in Mice

Abstract

Background: Japanese cedar (Cryptomeria japonica; CJ) pollinosis is one of the most common allergic diseases in Japan. B cell epitopes on Cry j 1, a major allergen of CJ pollen, have been analyzed by the specific monoclonal antibodies to Cry j 1, and most of these epitopes may be conformational, but no previous report has addressed the analysis of sequential epitope mapping with synthetic peptides. The main purpose of the present study is to identify IgE and IgG B cell epitopes on Cry j 1 by using a synthetic peptide approach in mice. Methods: We synthesized 35 overlapping peptides that cover the entire length of Cry j 1 and examined whether mouse IgE and IgG antibodies produced by immunization with Cry j 1 reacted to the Cry j 1 peptides. Results and Conclusion: We found that mouse IgE and IgG antibodies reacted strongly to Cry j 1 peptide No. 15 (¹⁴¹GVEPVHPQDGDALTLRTATN¹⁶⁰), though those antibodies did not react with other peptides. IgE and IgG antibody binding to peptide No. 15 was completely inhibited by Cry j 1 and the peptide. To determine the minimum epitope in peptide No. 15, we conducted an ELISA inhibition test. IgE and IgG antibody binding to peptide No. 15 was inhibited by smaller peptides of this peptide. We found the core of the epitope to be ¹⁴⁵VHPQDGDA¹⁵².