title: [An indirect ELISA using Legionella pneumophila recombinant MOMP protein and its application in serological diagnosis].
abstract: OBJECTIVE
  To express and purify the recombinant major outer membrane protein (MOMP) of Legionella pneumophila (Lp) as diagnostic antigen, and explore its practical value in the serological diagnosis of Lp infection.
  
  
  METHODS
  The recombinant plasmid pET-momp was transformed into the E.coli BL21 competent cells. The recombinant MOMP was induced to express, and then analyzed by SDS-PAGE electrophoresis, purified by affinity chromatography. We screened and obtained 58 positive blood serum and 32 negative blood serum using the DRG (Germany, IgG/IgM/IgA) Lp kit. The blood serum samples were detected for IgG, IgM, IgA antibody levels by indirect ELISA that we had established with the purified MOMP as the coating antigen, as well as by R&D (USA, IgG/IgM/IgA) Lp kit. Then using the receiver operating characteristic (ROC) curve, we compared these two methods in the sensitivity, specificity and consistency of the test results, for evaluating the application value of the indirect ELISA of recombinant MOMP.
  
  
  RESULTS
  The approximately 45 000 recombinant MOMP was successfully expressed and purified. Compared with the indirect ELISA we established with the R&D Lp kit for detecting Lp antibody IgG, IgM and IgA in blood serum, the sensitivity of the indirect ELISA of recombinant MOMP to IgG was 90.9%, the specificity was 91.7%, the Kappa value was 0.784 (P < 0.05), and the area under the ROC curve was 0.913; the sensitivity to IgM was 91.4% and the specificity was 90.6%, the Kappa value was 0.809 (P < 0.05), and the area under the ROC curve was 0.910; the sensitivity to IgA was 92.1% and the specificity was 88.9%, the Kappa value was 0.793(P < 0.05), and the area under the ROC curve was 0.905.
  
  
  CONCLUSIONS
  The recombinant MOMP was successfully induced to express and purified. The indirect ELISA we established with the recombinant MOMP protein as a diagnostic antigen showed good specificity, sensitivity and consistency, which laid a foundation for the development of serological diagnosis kit of Legionnaires' disease.
authors: Department of Pathogenic Biology and Immunology, School of Basic Medicine, Ningxia Medical University, Yinchuan 750004, China.
authors: Tao
authors: T
authors: Wang
authors: Caixia
authors: C
authors: Zhang
authors: Xiuqin
authors: X
authors: Cao
authors: Zhiwei
authors: Z
authors: Yang
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D004926:Escherichia coli / Q000235:genetics; D006801:Humans; D007132:Immunoglobulin Isotypes / Q000097:blood; D016952:Legionella pneumophila; D018272:Porins / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D012698:Serologic Tests / Q000379:methods*
chemical_list: D001426:Bacterial Proteins; D007132:Immunoglobulin Isotypes; D018272:Porins; D011994:Recombinant Proteins; C072453:major outer membrane protein, Legionella pneumophila