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Keywords:

  • IgE-binding regions;
  • Indian jujube;
  • latex–fruit syndrome;
  • recombinant Ziz m 1 allergen;
  • synthetic peptides

Summary

Ziz m 1 is a major Indian jujube (Zizyphus mauritiana) allergen involved in latex-fruit syndrome, and cDNA of the allergen has been cloned, sequenced and expressed in yeast by our laboratory previously. In this study, we performed an immunoglobulin E (IgE)-binding epitope analysis of Ziz m 1 using overlapping recombinant fragments. Eight overlapping recombinant fragments were generated from the recombinant Ziz m 1 allergen. The fragments were expressed in Escherichia coli and IgE-binding activities were evaluated by sera of latex–Indian jujube-allergic subjects and normal subjects using immunoblotting. Human allergic sera are not able to recognize fragments consisting of amino acid sequences 26–71, 119–280 and 119–291. However, residues at positions 26–199, 26–105, 26–86, 119–320 and 238–330 were found relevant in the IgE-binding. Our results indicate that 72NISGHCSDCTFLGEE86 and 292VWNRYYDLKTNYSSSIILEYVNSGTKYLP320 of Ziz m 1 are the sequences required for human IgE binding. Four corresponding peptides, 72NISGHCSDCTE86, 292VWNRYYDLKT301, 300KTNYSSSIILEY311 and 309LEYVNSGTKYLP320, were synthesized, and these peptides reacted with 70%, 100%, 70% and 70% of 10 allergic sera tested, as revealed by enzyme-linked immunosorbent assay. Sensitization to 292VWNRYYDLKT301 correlated significantly with the presence of allergic symptoms (P < 0·001). These findings will be useful in designing diagnostic and therapeutic approaches, thereby contributing to the development of specific immunotherapy for subjects with latex–fruit syndrome.