title: Molecular, Structural and Immunological Characterization of Der p 18, a Chitinase-Like House Dust Mite Allergen.
abstract: BACKGROUND
  The house dust mite (HDM) allergen Der p 18 belongs to the glycoside hydrolase family 18 chitinases. The relevance of Der p 18 for house dust mite allergic patients has only been partly investigated.
  
  
  OBJECTIVE
  To perform a detailed characterization of Der p 18 on a molecular, structural and immunological level.
  
  
  METHODS
  Der p 18 was expressed in E. coli, purified to homogeneity, tested for chitin-binding activity and its secondary structure was analyzed by circular dichroism. Der p 18-specific IgG antibodies were produced in rabbits to localize the allergen in mites using immunogold electron microscopy and to search for cross-reactive allergens in other allergen sources (i.e. mites, crustacea, mollusca and insects). IgE reactivity of rDer p 18 was tested with sera from clinically well characterized HDM-allergic patients (n = 98) and its allergenic activity was analyzed in basophil activation experiments.
  
  
  RESULTS
  Recombinant Der p 18 was expressed and purified as a folded, biologically active protein. It shows weak chitin-binding activity and partial cross-reactivity with Der f 18 from D. farinae but not with proteins from the other tested allergen sources. The allergen was mainly localized in the peritrophic matrix of the HDM gut and to a lower extent in fecal pellets. Der p 18 reacted with IgE from 10% of mite allergic patients from Austria and showed allergenic activity when tested for basophil activation in Der p 18-sensitized patients.
  
  
  CONCLUSIONS
  Der p 18 is a rather genus-specific minor allergen with weak chitin-binding activity but exhibits allergenic activity and therefore should be included in diagnostic test panels for HDM allergy.
authors.affiliation: Division of Immunopathology, Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Resch
authors.affiliation: Division of Hematology and Hemostaseology, Department of Internal Medicine I, Medical University of Vienna, Vienna, Austria.
authors.forename: Katharina
authors.initials: K
authors.lastname: Blatt
authors.affiliation: Institute of Medical Physics and Biophysics, University of Münster, Münster, Germany.
authors.forename: Ursula
authors.initials: U
authors.lastname: Malkus
authors.affiliation: Division of Structural Biology, Institute of Molecular Biosciences, University of Graz, Graz, Austria.
authors.forename: Christian
authors.initials: C
authors.lastname: Fercher
authors.affiliation: Division of Immunopathology, Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria.
authors.forename: Ines
authors.initials: I
authors.lastname: Swoboda
authors.affiliation: Division of Immunopathology, Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria.
authors.forename: Margit
authors.initials: M
authors.lastname: Focke-Tejkl
authors.affiliation: Division of Immunopathology, Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria.
authors.forename: Kuan-Wei
authors.initials: KW
authors.lastname: Chen
authors.affiliation: Division of Immunopathology, Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria.
authors.forename: Susanne
authors.initials: S
authors.lastname: Seiberler
authors.affiliation: Division of Immunopathology, Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria.
authors.forename: Irene
authors.initials: I
authors.lastname: Mittermann
authors.affiliation: Division of Immunopathology, Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria.
authors.forename: Christian
authors.initials: C
authors.lastname: Lupinek
authors.affiliation: Division of Immunopathology, Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria.
authors.forename: Azahara
authors.initials: A
authors.lastname: Rodriguez-Dominguez
authors.affiliation: Vienna Challenge Chamber, Vienna, Austria.
authors.forename: Petra
authors.initials: P
authors.lastname: Zieglmayer
authors.affiliation: Vienna Challenge Chamber, Vienna, Austria.
authors.forename: René
authors.initials: R
authors.lastname: Zieglmayer
authors.affiliation: Division of Structural Biology, Institute of Molecular Biosciences, University of Graz, Graz, Austria.
authors.forename: Walter
authors.initials: W
authors.lastname: Keller
authors.affiliation: Institute of Scientific Instruments of the ASCR, Academy of Sciences of the Czech Republic, Brno, Czech Republic.
authors.forename: Vladislav
authors.initials: V
authors.lastname: Krzyzanek
authors.affiliation: Division of Hematology and Hemostaseology, Department of Internal Medicine I, Medical University of Vienna, Vienna, Austria.
authors.forename: Peter
authors.initials: P
authors.lastname: Valent
authors.affiliation: Division of Immunopathology, Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria.
authors.forename: Rudolf
authors.initials: R
authors.lastname: Valenta
authors.affiliation: Division of Immunopathology, Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria.|Christian Doppler Laboratory for the Development of Allergen Chips, Medical University of Vienna, Austria.
authors.forename: Susanne
authors.initials: S
authors.lastname: Vrtala
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000097:blood / Q000737:chemistry / Q000302:isolation & purification; D039741:Antigens, Dermatophagoides / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D060829:Arthropod Proteins / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D001491:Basophils / Q000166:cytology / Q000187:drug effects / Q000276:immunology; D002686:Chitin / Q000737:chemistry* / Q000276:immunology; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005260:Female; D015870:Gene Expression; D006801:Humans; D007106:Immune Sera / Q000737:chemistry; D008297:Male; D011485:Protein Binding; D000072756:Protein Conformation, alpha-Helical; D000072757:Protein Conformation, beta-Strand; D017510:Protein Folding; D054730:Protein Interaction Domains and Motifs; D039981:Pyroglyphidae / Q000737:chemistry* / Q000648:ultrastructure; D011817:Rabbits; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D012130:Respiratory Hypersensitivity / Q000139:chemically induced / Q000276:immunology* / Q000503:physiopathology; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D000906:Antibodies; D039741:Antigens, Dermatophagoides; D060829:Arthropod Proteins; C514375:Der p 18 allergen, Dermatophagoides pteronyssinus; D007106:Immune Sera; D011994:Recombinant Proteins; D002686:Chitin