Fine mapping and structural analysis of immunodominant IgE allergenic epitopes in chicken egg ovalbumin

Ovalbumin is a major allergen in hen egg white that causes IgE-mediatedfood allergic reactions in children. In this study, the immunodominantIgE-binding epitopes of ovalbumin were mapped using arrays ofoverlapping peptides synthesized on activated cellulose membranes.Pooled human sera from 18 patients with egg allergy were usedto probe the membrane. Five distinct regions were found to containdominant allergic IgE epitopes, these being L38T49, D95A102,E191V200, V243E248 and G251N260. The critical amino acids involvedin IgE antibody binding were also determined. These epitopeswere composed primarily of hydrophobic amino acids, followedby polar and charged residues and being comprised of ß-sheetand ß-turn structures. One epitope, D95A102, consistedof a single -helix. These results provide useful informationon the functional role of amino acid residues to evaluate thestructure–function relationships and structural propertiesof allergic epitopes in ovalbumin. They also provide a strategicapproach for engineering ovalbumin to reduce its allergenicity. Received January 9, 2003; revised April 23, 2003; accepted August 28, 2003.