Immune Response of Individuals Vaccinated With Hypoallergenic Derivatives of the Major Birch Pollen Allergen, Bet v 1

The only disease-modifying treatment for allergic disorders nowadays is allergen-specific immunotherapy (SIT). To induce hyporesponsiveness increasing doses of the disease-eliciting allergens are applied. One major problem of this treatment is, that it has to combat with an already established immune response against the disease-eliciting allergen. To circumvent this problem the investigators want to perform the proof of principle study towards prophylactic treatment. Prophylactic vaccination is used since many years for many infectious diseases. The investigators want to adopt this successful principle for the treatment of type I allergies. For this purpose non-allergic healthy individuals will be immunized with adjuvant-bound hypoallergenic derivatives of the major birch pollen allergen, Bet v 1. As usual for allergen-specific immunotherapy, injections will be applied subcutaneously. Three injections in one-monthly intervals will be given to establish the immune response and a further injection after one year will determine how the vaccine-induced immune response can be boosted. The vaccine will be composed of an equimolar mixture of two adjuvant-bound hypoallergenic derivatives of the major birch pollen allergen, Bet v 1. The first investigational product (IP) designated as Bet v 1aF1 is a protein of 73 amino acid residues and represents the first half (1-73aa) of the Bet v 1 molecule. The second IP, Bet v 1aF2, is a protein of 86 amino acid residues and represents the second half (74-160aa) of Bet v 1. Both proteins are expressed in Escherichia coli. The hypoallergenic derivatives lost their IgE binding capacities by the disruption of the conformational IgE epitopes of the Bet v 1 molecule. In several preclinical and clinical studies it has been shown that the two hypoallergenic fragments, Bet v 1aF1 and Bet v 1aF2 have a strongly reduced allergenic reactivity and almost no sensitization potential, requisite for a prophylactic treatment. In a multi-centre pla