Development and characterization of a recombinant, hypoallergenic, peptide-based vaccine for grass pollen allergy.

BACKGROUND: Grass pollen is one of the most important sources of respiratory allergies worldwide. OBJECTIVE: This study describes the development of a grass pollen allergy vaccine based on recombinant hypoallergenic derivatives of the major timothy grass pollen allergens Phl p 1, Phl p 2, Phl p 5, and Phl p 6 by using a peptide-carrier approach. METHODS: Fusion proteins consisting of nonallergenic peptides from the 4 major timothy grass pollen allergens and the PreS protein from hepatitis B virus as a carrier were expressed in Escherichia coli and purified by means of chromatography. Recombinant PreS fusion proteins were tested for allergenic activity and T-cell activation by means of IgE serology, basophil activation testing, T-cell proliferation assays, and xMAP Luminex technology in patients with grass pollen allergy. Rabbits were immunized with PreS fusion proteins to characterize their immunogenicity. RESULTS: Ten hypoallergenic PreS fusion proteins were constructed, expressed, and purified. According to immunogenicity and induction of allergen-specific blocking IgG antibodies, 4 hypoallergenic fusion proteins (BM321, BM322, BM325, and BM326) representing Phl p 1, Phl p 2, Phl p 5, and Phl p 6 were included as components in the vaccine termed BM32. BM321, BM322, BM325, and BM326 showed almost completely abolished allergenic activity and induced significantly reduced T-cell proliferation and release of proinflammatory cytokines in patients' PBMCs compared with grass pollen allergens. On immunization, they induced allergen-specific IgG antibodies, which inhibited patients' IgE binding to all 4 major allergens of grass pollen, as well as allergen-induced basophil activation. CONCLUSION: A recombinant hypoallergenic grass pollen allergy vaccine (BM32) consisting of 4 recombinant PreS-fused grass pollen allergen peptides was developed for safe immunotherapy of grass pollen allergy.

Hypoallergenic derivatives of the major birch pollen allergen Bet v 1 obtained by rational sequence reassembly.

BACKGROUND: At least 100 million patients suffer from birch pollen allergy. OBJECTIVE: Rational design of recombinant derivatives of the major birch pollen allergen, Bet v 1, characterized by reduced IgE reactivity, preservation of sequences relevant for the induction of allergen-specific blocking IgG, and maintenance of T-cell epitopes for immunotherapy of birch pollen allergy. METHODS: Three recombinant mosaic proteins derived from Bet v 1 were generated by reassembly of codon-optimized genes coding for Bet v 1 fragments containing the elements for the induction of allergen-specific blocking IgG antibodies and the major T-cell epitopes. The proteins were expressed in Escherichia coli as recombinant mosaic molecules and compared with the Bet v 1 wild-type protein by chemical and structural methods, regarding IgE-binding and IgG-binding capacity, in basophil activation assays and tested for the in vivo induction of IgG responses. RESULTS: Three recombinant Bet v 1 (rBet v 1) mosaic proteins with strongly reduced IgE reactivity and allergenic activity were expressed and purified. Immunization with the recombinant hypoallergens induced IgG antibodies that inhibited IgE reactivity of patients with allergy to Bet v 1 comparable to those induced with the rBet v 1 wild-type allergen. CONCLUSION: We report the generation and preclinical characterization of 3 hypoallergenic rBet v 1 derivatives with suitable properties for immunotherapy of birch pollen allergy.

Structure of the major carrot allergen Dau c 1.

Dau c 1 is a major allergen of carrot (Daucus carota) which displays IgE cross-reactivity with the homologous major birch-pollen allergen Bet v 1. The crystal structure of Dau c 1 has been determined to a resolution of 2.7 A, revealing tight dimers. The structure of Dau c 1 is similar to those of the major allergens from celery, Api g 1, and birch pollen, Bet v 1. Electron density has been observed in the hydrophobic cavity of each monomer and has been modelled with polyethylene glycol oligomers of varying length. Comparison of the surface topology and physicochemical properties of Dau c 1 and Bet v 1 revealed that they may have some, but not all, epitopes in common. This is in agreement with the observation that the majority of carrot-allergic patients have Bet v 1 cross-reactive IgE antibodies, whereas others have Dau c 1-specific IgE antibodies which do not recognize Bet v 1.