Bases moleculaires de la réactivité croisée entre Act c 12 et les allergènes globulines 11S des graines : identification in silico des épitopes B d'Act c 12

Kiwi fruit (Actinidia deliciosa, A. chinensis) is an important source of food allergy in children and adults in Western countries. The allergens responsible for this food allergy consist primarily of typical fruit allergens, e.g. the PR10 Bet v 1-like allergen Act d 8, the cysteine protease actinidin Act d 1, the TLP Act d 2, and a chitinase. All of these allergens from A. deliciosa fruits have their counterparts in A. chinensis fruits. Recently, two other allergens belonging to the cupin superfamily (Act c 12) and the 2S albumin family (Act c 13), found in the kernels of A. chinensis fruit, have been identified as hidden fruit allergens responsible for IgE-binding cross-reactivity with peanuts and tree nuts. The sequential IgE-binding epitope regions of Act c 12 were predicted using a combination of in silico predictive approaches. Sequential IgE-binding epitopes of Act c 12 were predicted on a three-dimensional model of the protein from the amino acid sequence comparisons of the IgE-binding regions of cross-reacting cupins of peanuts and tree nuts. Residues of the sequence stretches exposed at the molecular surface were assigned as cross-reacting IgE-binding regions of Act c 12. In addition to their conformational similarities, these putative IgE-binding epitopes share a high degree of sequence similarity with the corresponding IgE-binding regions of peanut and tree-nut cupin allergens. The Act c 12 allergen offers an interesting example of a hidden fruit allergen likely to trigger allergic responses in individuals previously sensitized to peanut and other three-nut cupin allergens.