Major Allergen and Its IgE Cross-Reactivity among Salmonid Fish Roe Allergy

Yolk protein extracts were prepared from four kinds of salmonid fish roes, and the proteins that reacted with IgE were screened by immunoblotting using sera from 20 patients allergic to chum salmon roe. IgE cross-reactivities among the salmonid yolk proteins were also investigated by competitive ELISA. The results were as follows: (1) The major protein components in salmonid roes were lipovitellin and β′-component, which are subfragments of vitellogenin. (2) Most sera from the patients showed IgE reactivity to β′-component in all yolk protein extracts, and some of them also reacted to lipovitellin heavy chain or its light chain. (3) Salmonid β′-component showed high similarity (>90%) in the N-terminal amino acid sequence. (4) All of the salmonid yolk protein extracts inhibited the IgE reaction between patient sera and the chum salmon β′-component. These findings indicate that the β′-component in salmonid roe is a common major allergen with strong IgE cross-reactivity.