Molecular basis of the allergenicity and cross-reactivity of a major allergen-Crassostrea gigas arginine kinase

As an important shellfish group, the oyster can induce severe allergic reactions. We aimed to identify and characterize the major allergen in Crassostrea gigas, and elucidate the molecular basis of its allergenicity and cross-reactivity. The native and recombinant C. gigas-arginine kinase (AK) displayed significant immunoglobulin (Ig)G- and IgE-binding activity. The IgE-binding activity of C. gigas-AK could be reduced by thermal treatment and strong acidic and alkaline conditions. Besides, cross-reactivity of AK was demonstrated between shellfish species. Among seven epitope peptides identified here, P2 is responsible for the specificity of C. gigas-AK, while P3 is responsible for cross-reactions between mollusks and crustaceans. Furthermore, Glu98 and His31 in the light chain, Arg101, and Lys57 in the heavy chain are identified as key IgE residues in recognizing epitopes. These findings provide new insights into the prevention and treatment of shellfish allergy and the development of hypoallergenic shellfish products.