Pollen-related food allergy: cloning and immunological analysis of isoforms and mutants of Mal d 1, the major apple allergen, and Bet v 1, the major birch pollen allergen

Abstract

We conclude that divergent allergenicity of apple strains mainly depends on different expression levels of the major allergen. Introduction of a proline residue in position 111 of Mal d 1 and in position 112 of Bet v 1 led to a drastic reduction of allergenicity of both the pollen and the food allergen, obviously also removing the cross-reactive epitope. Mutants with reduced IgE-reactivity but maintained T-cell reactivity may represent new candidates for a safer specific immunotherapy with reduced side-effects.

Mutational epitope analysis of Pru av 1 and Api g 1, the major allergens of cherry (Prunus avium) and celery (Apium graveolens): correlating IgE reactivity with three-dimensional structure

“…However, results of tests in vivo with hypo-allergenic variants of food allergens have not been published so far. Furthermore, the results of this and previous studies [14,16] remind us that the IgE-binding epitopes are highly patient specific and site-directed mutagenesis can also enhance the IgE reactivity for at least a subgroup of patients, as observed for Pru av 1 Trp 45 ( Figure 3A) and Api g 1 Glu 44 ( Figure 3B). Hence, with allergens containing exclusively conformational IgE-binding epitopes, hypo-allergenic variants may be produced more easily by irreversibly preventing the folding process, as in the case of Pru av 1 Pro 112 , than by mutation of all assumed IgE-binding epitopes while maintaining the native tertiary structure.…”

“…our previous observation that the mutation of Thr 10 to Pro does not affect the IgE-binding capacity of Pru av 1 [14], this suggests that the region on the adjacent first and seventh β-strands around Thr 10 and Ser 112 , which was suggested as a potential IgE-binding epitope of Bet v 1 [15], Mal d 1 [16] and Api g 1.0101 [12], does not constitute a clinically relevant cross-reactive IgE-binding epitope of Pru av 1.…”

“…This prompted us to postulate the P-loop around Glu 45 as one of at least two conformational crossreactive IgE epitopes of Pru av 1 and hence a promising candidate for site-directed mutagenesis to alter the IgE-binding properties of Pru av 1 [7]. Based on mutational studies of the weakly IgEbinding isoform Bet v 1d [15], Mal d 1 [16] from apple (Malus domestica) and Api g 1.0101 [12], a region on the adjacent first and seventh β-strands around Thr 10 and Ser 112 respectively, was also proposed as a cross-reactive IgE epitope of Pru av 1 [14].…”

Potential, pitfalls, and prospects of food allergy diagnostics with recombinant allergens or synthetic sequential epitopes

“…[10], [120], [121], [122] and [123] [124], [125], [126], [127], [128], [129] and [130] However, other studies at different shifting offsets, with different peptides sizes, or both revealed different sets of immunodominant sequential epitopes for the same allergens. [29], [124], [125], [126], [127], [130] and [131] Nevertheless, approaches to use these alleged immunodominant peptides for the risk assessment of life-threatening symptoms, as well as the prediction of persistence in food hypersensitivity, were apparently successful.…”

Investigation of Mal d 1 Allelic Variants and Phylogenetic Diversity in Contemporary and Historical Polish Apple Cultivars

“…Studies done by Son et al (1999) showed that allergenic differences between apple cultivars are mainly related to the expression levels of Mal d 1 and not to the presence of different isoformes, whereas Gao et al (2008) stated that differences in allergenicity are associated with the allelic composition of two specific genes (Mal d 1.04 and Mal d 1 1.06 A).…”