Fra a 1.02 Is the Most Potent Isoform of the Betv1-like Allergen in Strawberry Fruit.

Abstract

The strawberry fruit proteins Fra a 1.01E-1.08 are homologues of the major birch pollen allergen Bet v 1. Three of the proteins are known to have essential biological functions in pigment formation during fruit ripening and seem to be responsible for allergic reactions to strawberry fruit. We evaluated the cross-reactive allergenic potential of these putative strawberry allergens in patients allergic to birch pollen. Activation of basophils of eight atopic patients was studied using different concentrations of Fraa1 isoforms. Betv1a was used as control and as atopic patient selection criterion. Although Fraa1.01E-1.08 have amino acid sequence identities of 74.5-97.5% with Fraa1.02, the basophil activation mediated by the eight Fraa1 proteins differed substantially. Fraa1.03 and Fraa1.02 showed the highest activation of basophils, 73 and 66% of total basophils, respectively. On the basis of the high relative expression of the gene Fraa1.02 in ripe strawberry fruits of allergenic varieties, Fraa1.02 was identified as the main strawberry allergen of the Betv1 superfamily. Knowledge of the allergenic potential of Fraa1.02/1.03 will help to improve food safety and can serve as a valuable marker for the development of red-fruited hypoallergenic strawberry cultivars.