Identification of the major allergenic epitopes of Eriocheir sinensis roe hemocyanin: A novel tool for food allergy diagnoses

•The epitopes and the recombinant allergen comprising the immunodominant epitopes of hemocyanin are described for the first time.•This article focuses on crab roe, which has not been done in the past.•The recombinant allergen will allow us to develop more specific diagnostic and therapeutic approaches compared to crude extracts.

Crab meat and roe are highly nutritious delicacies in China. While extensive research has been conducted for allergens derived from crab-meat, data relevant to the allergenic potential of crab roe derived proteins, of which hemocyanin is a principal contender, are almost entirely absent. Using bioinformatics prediction and IgE-binding assays, the three principal immunodominant epitopes of hemocyanin were identified and then combined as a single recombinant fusion protein (rHc). This together with the full-length recombinant protein (Hc) were expressed in Escherichia coli and subsequently identified by SDS-PAGE and immunoblotting. Ninety-five percent of our patients were found to carry rHc-specific IgE antibodies by ELISA. Dot-blot inhibition, together with ELISA inhibition studies, showed that pre-incubation of patient sera with the recombinant epitope protein could inhibit26% to 63% (mean: 50%) of IgE binding to immobilized, full-length Hc and the dose-response curve represents as a sigmoid shape. The recombinant protein (rHc) represents a versatile biologic tool with which to diagnose and investigate therapies for E. sinensis allergy.