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. 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.
Research Department, ALK-Abelló, Hørsholm, Denmark. jho@dk.alk-abello.com
Jens
J
Holm
Michael
M
Gajhede
Mercedes
M
Ferreras
Anette
A
Henriksen
Henrik
H
Ipsen
Jørgen N
JN
Larsen
Lise
L
Lund
Henrik
H
Jacobi
Anders
A
Millner
Peter A
PA
Würtzen
Michael D
MD
Spangfort
D000485:Allergens / Q000737:chemistry / Q000276:immunology*; D000595:Amino Acid Sequence; D000818:Animals; D000917:Antibody Formation; D052179:Antigens, Plant; D001491:Basophils / Q000378:metabolism; D006636:Histamine Release; D006801:Humans; D007114:Immunization; D007073:Immunoglobulin E / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D015202:Protein Engineering; D017510:Protein Folding; D013601:T-Lymphocytes / Q000276:immunology; D014614:Vaccines, Synthetic / Q000276:immunology*
D000485:Allergens; D052179:Antigens, Plant; D014614:Vaccines, Synthetic; D007073:Immunoglobulin E