title: Chimeras of Bet v 1 and Api g 1 reveal heterogeneous IgE responses in patients with birch pollen allergy.
abstract: BACKGROUND
  Characterization of IgE-binding epitopes of allergens and determination of their patient-specific relevance is crucial for the diagnosis and treatment of allergy.
  
  
  OBJECTIVE
  We sought to assess the contribution of specific surface areas of the major birch pollen allergen Bet v 1.0101 to binding IgE of individual patients.
  
  
  METHODS
  Four distinct areas of Bet v 1 representing in total 81% of its surface were grafted onto the scaffold of its homolog, Api g 1.0101, to yield the chimeras Api-Bet-1 to Api-Bet-4. The chimeras were expressed in Escherichia coli and purified. IgE binding of 64 sera from Bet v 1-sensitized subjects with birch pollen allergy was determined by using direct ELISA. Specificity was assessed by means of inhibition ELISA.
  
  
  RESULTS
  rApi g 1.0101, Api-Bet-1, Api-Bet-2, Api-Bet-3, and Api-Bet-4 bound IgE from 44%, 89%, 80%, 78%, and 48% of the patients, respectively. By comparing the amount of IgE binding to the chimeras and to rApi g 1.0101, 81%, 70%, 75%, and 45% of the patients showed significantly enhanced IgE binding to Api-Bet-1, Api-Bet-2, Api-Bet-3, and Api-Bet-4, respectively. The minority (8%) of the sera revealed enhanced IgE binding exclusively to a single chimera, whereas 31% showed increased IgE binding to all 4 chimeras compared with rApi g 1.0101. The chimeras inhibited up to 70% of IgE binding to rBet v 1.0101, confirming the specific IgE recognition of the grafted regions.
  
  
  CONCLUSIONS
  The Bet v 1-specific IgE response is polyclonal, and epitopes are spread across the entire Bet v 1 surface. Furthermore, the IgE recognition profile of Bet v 1 is highly patient specific.
authors: Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria.
authors: Barbara
authors: B
authors: Gepp
authors: Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria.
authors: Nina
authors: N
authors: Lengger
authors: Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria.
authors: Merima
authors: M
authors: Bublin
authors: Floridsdorfer Allergiezentrum, Vienna, Austria.
authors: Wolfgang
authors: W
authors: Hemmer
authors: Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria. Electronic address: heimo.breiteneder@meduniwien.ac.at.
authors: Heimo
authors: H
authors: Breiteneder
authors: Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria.
authors: Christian
authors: C
authors: Radauer
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000485:Allergens / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D000595:Amino Acid Sequence; D000818:Animals; D000918:Antibody Specificity; D052179:Antigens, Plant / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D001666:Binding Sites, Antibody; D002648:Child; D002678:Chimera / Q000235:genetics / Q000276:immunology*; D000939:Epitopes / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005260:Female; D018740:Genetic Heterogeneity; D006801:Humans; D007106:Immune Sera / Q000737:chemistry; D007073:Immunoglobulin E / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D011485:Protein Binding; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D012189:Retrospective Studies; D006255:Rhinitis, Allergic, Seasonal / Q000235:genetics / Q000276:immunology* / Q000473:pathology; D017386:Sequence Homology, Amino Acid
chemical_list: D000485:Allergens; D052179:Antigens, Plant; C096695:Api g 1 protein, Apium graveolens; D000939:Epitopes; D007106:Immune Sera; D010940:Plant Proteins; D011994:Recombinant Proteins; C061312:Bet v 1 allergen, Betula; D007073:Immunoglobulin E
keywords: Api g 1.0101; Bet v 1.0101; IgE epitope mapping; birch pollen allergy; chimera-based technology; patient-specific IgE repertoire