title: Blomia tropicalis Blo t 5 and Blo t 21 recombinant allergens might confer higher specificity to serodiagnostic assays than whole mite extract.
abstract: BACKGROUND
  Blomia tropicalis is a dust mite and an important source of allergens in tropical regions. Up to now, the assays to diagnose atopy to this mite use whole body extract as antigens. However, anti-B. tropicalis IgE antibodies cross-react with Ascaris lumbricoides antigens, hindering the diagnosis of allergy to this mite. In this study, B. tropicalis recombinant allergens were evaluated with the purpose of developing an immunodiagnostic assay for allergy to this mite with greater specificity than those commercially available.
  
  
  METHODS
  Two B. tropicalis allergens (Blo t 5 and Blo t 21) were cloned into a plasmidial expression vector, expressed in Escherichia coli and purified by affinity chromatography. Sixty-three sera containing anti-B. tropicalis extract (BtE) IgE antibodies were used to investigate IgE reactivity to the recombinant Blot 5 and 21 allergens. Inhibition assays with 20 sera pre-adsorbed with A. lumbricoides extract were performed using rBlo t 5, rBlo t 21, and BtE as antigens. All the assays were carried using indirect ELISA.
  
  
  RESULTS
  Eighty-two point nine percent and 80.0% of the sera with anti-BtE antibodies from 35 children reacted with rBlo t 5 and rBlo t 21, respectively, whereas 92.8% and 89.3% of the 28 sera with anti-BtE antibodies from adult asthma patients reacted with the same allergens, and 96.4% of these sera reacted with a mixture of rBlo t 5 and rBlo t 21. In an inhibition ELISA, the absorption of sera by A. lumbricoides extract affected less the reaction with rBlo t 5 and rBlo t 21 than with BtE.
  
  
  CONCLUSIONS
  The rBlo t 5 and rBlo t 21 allergens contain important epitopes recognized by IgE antibodies of individuals allergic to B. tropicalis antigens. Moreover, the assays using the recombinant allergens had lower IgE cross-reactivity with A. lumbricoides antigens, a fact which would confers higher specificity to serodiagnostic assays than the crude mite extract. However, additional recombinant allergens should be evaluated in order to reach the same sensitivity of the commercially available assays based on mite extract.
authors: Laboratório de Alergia e Acarologia, Instituto de Ciências da Saúde, Universidade Federal da Bahia, Avenida Reitor Miguel Calmon, sem nº, Canela, Salvador, Bahia CEP 40110-100, Brazil.
authors: Kellyanne dos Anjos
authors: Kdos A
authors: Carvalho
authors: Osvaldo Pompílio
authors: OP
authors: de Melo-Neto
authors: Franklin Barbalho
authors: FB
authors: Magalhães
authors: João Carlos Marques
authors: JC
authors: Ponte
authors: Filipe Adriano Borba
authors: FA
authors: Felipe
authors: Mariese Conceição Alves
authors: MC
authors: dos Santos
authors: Givaneide
authors: G
authors: dos Santos Lima
authors: Álvaro Augusto
authors: ÁA
authors: Cruz
authors: Carina Silva
authors: CS
authors: Pinheiro
authors: Lain Carlos
authors: LC
authors: Pontes-de-Carvalho
authors: Neuza Maria
authors: NM
authors: Alcantara-Neves
mesh_terms: D000328:Adult; D000485:Allergens / Q000276:immunology*; D000818:Animals; D000947:Antigens, Helminth / Q000276:immunology; D001200:Ascaris / Q000276:immunology*; D002675:Child, Preschool; D045424:Complex Mixtures / Q000276:immunology*; D003429:Cross Reactions / Q000276:immunology; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology; D008925:Mites / Q000276:immunology*; D011993:Recombinant Fusion Proteins / Q000276:immunology* / Q000302:isolation & purification; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012698:Serologic Tests / Q000379:methods*
chemical_list: D000485:Allergens; D000947:Antigens, Helminth; D045424:Complex Mixtures; D011993:Recombinant Fusion Proteins; D007073:Immunoglobulin E