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Updated: May 15, 2026
Overlapping Peptide Library to Map Qa-1 Epitopes in a Protein
Published on: December 20, 2017
Mapping of the IgE and IgG4 sequential epitopes of ovomucoid with a peptide microarray immunoassay
Javier Martínez-Botas1, Inmaculada Cerecedo, Javier Zamora
1Servicio de Bioquímica-Investigación, Hospital Universitario Ramón y Cajal, IRYCIS, Madrid, España. javier.botas@hrc.es
Background:
Ovomucoid (Gal d 1) has been demonstrated to be the most important allergen in IgE-mediated egg allergy. Peptide microarray analysis is a novel method that can provide useful information on the nature of specific allergens.
Methods:
A peptide microarray immunoassay was performed using a 15- and 20-amino acid (aa) library of overlapping peptides (3-offset) of the primary sequence of ovomucoid. Sera from 50 patients with IgE-mediated egg allergy and reactivity to ovomucoid, with more than 1 year of follow-up, and sera from 10 controls were tested. Peptides were considered major epitopes when the average weighted Z-score was greater than 3 and recognized by at least 20% of the patient's sera. Specific IgE epitopes were established on the basis of the IgE/IgG4 Z-score ratio.
Results:
The IgE and IgG4 recognition pattern was similar in both sets of peptides, but the signal intensity was generally higher in the 20-aa set. Thirty-four percent of the patients did not recognize any IgE sequential peptide and 20% of the patients recognized more than 10 sequential peptides. We identified 3 major IgE B-cell epitopes in domains I and II of ovomucoid. IgE/IgG4 ratio analysis showed that peptides 1-2 (aa 4-20) and peptides 29-31 (aa 91-104) were specific IgE epitopes.
Conclusion:
By using peptide microarray immunoassay in egg-allergic patients, we established that 34% of the patients do not have any linear epitope recognized by IgE. Further studies are needed to determine the clinical relevance of this finding.
