title: Convenient, rapid and economic detection and semi-quantification of American cockroach allergen in the environment.
abstract: BACKGROUND
  Measuring allergen levels in the environment provides useful information to guide the management of allergic patients. A laboratory-based test kit sandwich ELISA for quantification of Per a 9, the major allergen of Periplaneta americana was recently developed. However, it is not suitable for screening.
  
  
  OBJECTIVE
  To develop a simple, rapid, and economic format for semi-quantification of Per a 9 assay using dot-blot ELISA technique.
  
  
  METHODS
  The efficacy of direct dot-blot ELISA and sandwich dot-blot ELISA was evaluated. Direct dot-blot ELISA was selected for further modification into 6 protocols. The selected protocol of direct dot-blot was further compared with the laboratory-based test kit, sandwich ELISA.
  
  
  RESULTS
  The lowest detection limits in protocols no. 1-6 were 3.9, 15.6, 15.6, 62.5, 125 and 62.5 microg/ml of native Per a 9 whereas time required for each protocol was 145, 45, 30, 26, 18 and 26 minutes, respectively. The sensitivity of direct dot-ELISA was 3.9 microg/ml of Per a 9. Protocol no. 3 was the most suitable assay because its detection limits were as low as 15.6 microg/ml of CR allergen and the total process took only 30 minutes. In comparison with the 2 days required for laboratory sandwich ELISA, the selected protocol provided a similar yield of allergen detection but it offers significant savings of time. Additionally, this method could be easily interpreted by various groups of people.
  
  
  CONCLUSIONS
  This modified direct dot-blot ELISA is the first membrane ELISA which is a semiquantitative test appropriate for screening American cockroach allergen owing to its simplicity, speed and good yield.
authors: Department of Parasitology, Faculty of Medicine Siriraj Hospital, Mahidol University, 2 Prannok Road, Bangkok Noi, Bangkok, Thailand. anchalee.tun@mahidol.ac.th
authors: Anchalee
authors: A
authors: Tungtrongchitr
authors: Nitat
authors: N
authors: Sookrung
authors: Wanpen
authors: W
authors: Chaicumpa
authors: Nitaya
authors: N
authors: Indrawattana
authors: Rotjana
authors: R
authors: Poolphol
authors: Nawannaporn
authors: N
authors: Sae-Lim
authors: Sirirat
authors: S
authors: Weeravejsukit
authors: G Chaweewan
authors: GC
authors: Bunnag
authors: Pakit
authors: P
authors: Vichyanond
mesh_terms: D000485:Allergens / Q000032:analysis* / Q000276:immunology; D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000276:immunology / Q000302:isolation & purification; D001122:Arginine Kinase / Q000032:analysis* / Q000276:immunology; D004391:Dust / Q000276:immunology; D004777:Environment; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D057166:High-Throughput Screening Assays; D006801:Humans; D006967:Hypersensitivity / Q000175:diagnosis / Q000276:immunology; D015151:Immunoblotting / Q000379:methods*; D057230:Limit of Detection; D015588:Observer Variation; D010526:Periplaneta / Q000737:chemistry* / Q000276:immunology; D011817:Rabbits; D013997:Time Factors
chemical_list: D000485:Allergens; D000911:Antibodies, Monoclonal; D004391:Dust; D001122:Arginine Kinase; C553356:Per a 9 allergen, Periplaneta americana