title: Epitope grafting, re-creating a conformational Bet v 1 antibody epitope on the surface of the homologous apple allergen Mal d 1.
abstract: Birch-allergic patients often experience oral allergy syndrome upon ingestion of vegetables and fruits, most prominently apple, that is caused by antibody cross-reactivity of the IgE antibodies in patients to proteins sharing molecular surface structures with the major birch pollen group 1 allergen from Betula verrucosa (Bet v 1). Still, to what extent two molecular surfaces need to be similar for clinically relevant antibody cross-reactivity to occur is unknown. Here, we describe the grafting of a defined conformational antibody epitope from Bet v 1 onto the surface of the homologous apple allergen Malus domestica group 1 (Mal d 1). Engineering of the epitope was accomplished by genetic engineering substituting amino acid residues in Mal d 1 differing between Bet v 1 and Mal d 1 within the epitope defined by the mAb BV16. The kinetic parameters characterizing the antibody binding interaction to Bet v 1 and to the mutated Mal d 1 variant, respectively, were assessed by Biacore experiments demonstrating indistinguishable binding kinetics. This demonstrates that a conformational epitope defined by a high affinity antibody-allergen interaction can successfully be grafted onto a homologous scaffold molecule without loss of epitope functionality. Furthermore, we show that increasing surface similarity to Bet v 1 of Mal d 1 variants by substitution of 6-8 residues increased the ability to trigger basophil histamine release with blood from birch-allergic patients not responding to natural Mal d 1. Conversely, reducing surface similarity to Bet v 1 of a Mal d 1 variant by substitution of three residues abolished histamine release in one patient reacting to Mal d 1.
authors: Research Department, ALK-ABELLÓ, Bøge Allé 6-8, DK-2970 Hørsholm, Denmark.
authors: Jens
authors: J
authors: Holm
authors: Mercedes
authors: M
authors: Ferreras
authors: Henrik
authors: H
authors: Ipsen
authors: Peter A
authors: PA
authors: Würtzen
authors: Michael
authors: M
authors: Gajhede
authors: Jørgen N
authors: JN
authors: Larsen
authors: Kaare
authors: K
authors: Lund
authors: Michael D
authors: MD
authors: Spangfort
mesh_terms: D000485:Allergens / Q000737:chemistry* / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D052179:Antigens, Plant / Q000737:chemistry* / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D000939:Epitopes / Q000737:chemistry* / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D006255:Rhinitis, Allergic, Seasonal / Q000097:blood / Q000235:genetics / Q000276:immunology
chemical_list: D000485:Allergens; D052179:Antigens, Plant; D000939:Epitopes; C095551:MALD1 protein, Malus domestica; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; C061312:Bet v 1 allergen, Betula; D007073:Immunoglobulin E