Allergy vaccine engineering: epitope modulation of recombinant Bet v 1 reduces IgE binding but retains protein folding pattern for induction of protective blocking-antibody responses.
Human type 1 immediate allergic response symptoms are caused by mediator release from basophils and mast cells. This event is triggered by allergens aggregating preformed IgE Abs bound to the high-affinity receptor (FcepsilonRI) on these cells. Thus, the allergen/IgE interaction is crucial for the cascade leading to the allergic and anaphylactic response ...
Human type 1 immediate allergic response symptoms are caused by mediator release from basophils and mast cells. This event is triggered by allergens aggregating preformed IgE Abs bound to the high-affinity receptor (FcepsilonRI) on these cells. Thus, the allergen/IgE interaction is crucial for the cascade leading to the allergic and anaphylactic response. Two genetically engineered forms of the white birch pollen major allergen Bet v 1 with point mutations directed at molecular surfaces have been characterized. Four and nine point mutations led to a significant reduction of the binding to human serum IgE, suggesting a mutation-induced distortion of IgE-binding B cell epitopes. In addition, the mutated allergens showed a decrease in anaphylactic potential, because histamine release from human basophils was significantly reduced. Retained alpha-carbon backbone folding pattern of the mutated allergens was indicated by x-ray diffraction analysis and circular dichroism spectroscopy. The rBet v 1 mutants were able to induce proliferation of T cell lines derived from birch pollen allergic patients. The stimulation indices were similar to the indices of nonmutated rBet v 1 and natural Bet v 1 purified from birch pollen. The ability of anti-rBet v 1 mutant specific mouse IgG serum to block binding of human serum IgE to rBet v 1 demonstrates that the engineered rBet v 1 mutants are able to induce Abs reactive with nonmodified Bet v 1. rBet v 1 mutants may constitute vaccine candidates with improved efficacy/safety profiles for safer allergy vaccination.
Related Citations:
X-Ray and NMR Structure of Bet V 1, the Origin of Birch Pollen Allergy Gajhede, M., Osmark, P., Poulsen, F.M., Ipsen, H., Larsen, J.N., Van Neerven, R.J.J., Schou, C., Lowenstein, H., Spangfort, M.D. (1996) Nat Struct Biol 3: 1040
Organizational Affiliation:
Research Department, ALK-Abelló, Hørsholm, Denmark. jho@dk.alk-abello.com
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