Par j 1 and Par j 2, the major allergens from Parietaria judaica pollen, have similar immunoglobulin E epitopes

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Abstract
Background Parietaria judaica is the main cause of allergy in Mediterranean countries. The major allergens from P. judaica pollen, Par j 1 and Par j 2, have amino acid sequence identity of 45% and contain eight cysteine residues involved in disulphide bonds that compact the structure. Objective The aim of the study was to identify IgE‐binding epitopes on Par j 1 and Par j 2, the major allergens from P. judaica pollen and correlate them with the three‐dimensional structure of the proteins. Methods Overlapping peptides representing the complete length of Par j 1 and Par j 2 were synthesized on a cellulose‐derivatized membrane. Sera from 17 P. judaica‐allergenic patients were used to identify IgE‐binding epitopes. Homology modelling of the three dimensional structure of both allergens was generated using the Swiss‐Model software on the basis of previously reported crystal structures. Results Five and eight IgE‐binding epitopes were identified on Par j 1 and Par j 2 allergens, respectively. Both proteins belonged to the non‐specific lipid transfer proteins (ns‐LTP) family and therefore a three‐dimensional model of both allergens was constructed on the basis of the maize ns‐LTP crystal structure. Par j 1 and Par j 2 allergens have three similar allergenic epitopes with high homology and identical conformation. Conclusion Three similar IgE‐epitopes of major allergens from P. judaica have been described. They could be good candidates for designing of IgE haptens as therapeutic agents with reduced anaphylactic side‐effects or for developing hypoallergenic variants of these major allergens.