title: Evaluation of immunoglobulin M and G Western blot and ELISA for screening antibodies to Treponema pallidum in blood donors.
abstract: BACKGROUND
  Enzyme-linked immunosorbent assay (ELISA) is the most popular method used by blood banks in China to screen for antibodies to Treponema pallidum (TP). However, this method produces a high percentage of false-positive reactions.The current study aimed to propose a more effective procedure for screening anti-TP antibodies in blood donors.
  
  
  METHODS
  A total of 1009 serum samples showing repeat reactivity in routine blood bank procedures were tested with a TP particle agglutination assay (TPPA) and 3 commercially available ELISA tests. Samples showing reactivity with any of these methods were further tested by Western blot (WB) and ELISA immunoglobulin G (IgG)and immunoglobulin M (IgM) anti-TP assays.
  
  
  RESULTS
  Of the 1009 samples tested, 170 were identified as reactive with at least one of our methods. In these 170 samples, excluding borderline cases, the agreement of the WB method with TPPA, Murex, BGI, and InTec ELISA tests was 76.0%, 77.8%, 78.4%, and 80.1%, respectively. With the WB results as the reference, the sensitivity of TPPA, Murex, BGI, and InTec ELISA tests was 91.5%, 95.4%, 99.2%, and 98.5%, respectively. TpN17 and TpN15 are the most important antigens in the antibody response of IgM and IgG, respectively. The WB IgM and IgG results suggest that the seroprevalence of anti-TP in blood donors in China is 0.49% (130/26,702).
  
  
  CONCLUSIONS
  A combination of routine ELISA methods and WB IgM and IgG may be a valid procedure for the confirmatory testing of anti-TP antibodies and would be beneficial for screening blood donors.
authors.affiliation: National Center for Clinical Laboratories, Beijing Hospital, Beijing 100730, People's Republic of China.
authors.forename: Lu-Nan
authors.initials: LN
authors.lastname: Wang
authors.forename: Jin-Ming
authors.initials: JM
authors.lastname: Li
mesh_terms: D000372:Agglutination Tests; D000907:Antibodies, Bacterial / Q000097:blood; D001782:Blood Donors; D015153:Blotting, Western / Q000379:methods*; D002681:China / Q000453:epidemiology; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D007075:Immunoglobulin M / Q000097:blood*; D008403:Mass Screening; D011933:Reagent Kits, Diagnostic; D012680:Sensitivity and Specificity; D013587:Syphilis / Q000175:diagnosis* / Q000453:epidemiology / Q000276:immunology; D013588:Syphilis Serodiagnosis / Q000379:methods; D014210:Treponema pallidum / Q000276:immunology*
chemical_list: D000907:Antibodies, Bacterial; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D011933:Reagent Kits, Diagnostic