Mechanisms of allergy/immunology
Tackling Bet v 1 and associated food allergies with a single hybrid protein

https://doi.org/10.1016/j.jaci.2016.09.055Get rights and content
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Background

Allergy vaccines should be easily applicable, safe, and efficacious. For Bet v 1–mediated birch pollen and associated food allergies, a single wild-type allergen does not provide a complete solution.

Objective

We aimed to combine immunologically relevant epitopes of Bet v 1 and the 2 clinically most important related food allergens from apple and hazelnut to a single hybrid protein, termed MBC4.

Methods

After identification of T cell epitope–containing parts on each of the 3 parental allergens, the hybrid molecule was designed to cover relevant epitopes and evaluated in silico. Thereby a mutation was introduced into the hybrid sequence, which should alter the secondary structure without compromising the immunogenic properties of the molecule.

Results

MBC4 and the parental allergens were purified to homogeneity. Analyses of secondary structure elements revealed substantial changes rendering the hybrid de facto nonreactive with patients' serum IgE. Nevertheless, the protein was monomeric in solution. MBC4 was able to activate T-cell lines from donors with birch pollen allergy and from mice immunized with the parental allergens. Moreover, on immunization of mice and rabbits, MBC4 induced cross-reactive IgG antibodies, which were able to block the binding of human serum IgE.

Conclusion

Directed epitope rearrangements combined with a knowledge-based structural modification resulted in a protein unable to bind IgE from allergic patients. Still, properties to activate specific T cells or induce blocking antibodies were conserved. This suggests that MBC4 is a suitable vaccine candidate for the simultaneous treatment of Bet v 1 and associated food allergies.

Key words

Birch pollen allergy
Bet v 1
birch pollen–associated food allergy
allergy vaccine candidate
molecular allergology

Abbreviations used

AIT
Allergen-specific immunotherapy
ANS
1-Anilino-8-naphthalene sulfonate
AP
Alkaline phosphatase
APC
Antigen-presenting cell
CD
Circular dichroism
PDB
Protein Data Bank
PFS
Pollen-food syndrome
RBL
Rat basophil leukemia
TCL
T-cell line
WT
Wild-type

Cited by (0)

Graphical abstract photos were purchased from Fotolia, and structural models were derived from the PBD entry 1bv1 (www.rcsb.org) and modified with UCSF Chimera 1.10.1 (www.cgl.ucsf.edu/chimera/).

Supported by the Austrian Science Fund (FWF) grant L688, the Austrian National Bank (ÖNB) grant 12533, and the priority program “Allergy-Cancer-BioNano Research Centre” of the University of Salzburg.

Disclosure of potential conflict of interest: H. Hofer received travel support from the European Academy of Allergy and Clinical Immunology (EAACI). M. Himly is an employee of the University of Salzburg, receives grant support from the Austrian Science Fund, and is the inventor of and patent holder for hypoallergenic molecules. T. Hawranek serves on the board for ALK-Abelló, Leti, and Novartis and receives payments for lectures from ALK-Abelló. B. Bohle receives grant support from the Austrian Science Funds and Christian Doppler Laboratory for Immunomodulation. F. Ferreira serves on the board form AllergenOnline Database, SIAF, and HAL Allergy. M. Wallner receives grant support from the Austrian National Bank. The rest of the authors declare that they have no relevant conflicts of interest.