Legionella Pneumophila MIP Protein Expression And Purification And Its Application In Serological Diagnosis

Objective：To expressed and purified protein of Legionella pneumophilaMIP, and explore its role in the serological diagnosis of Legionella pneumonia.Methods： The recombinant plasmid pET-mip was transformed intoE.coliBL21competent cells.The expression of MIP protein was induced, then useof SDS-PAGE electrophoresis to analysis, and purified by affinity chromatography.The purified MIP protein was the coating antigen,then the IgG、IgM、IgA antibodylevel of the filtered blood serum were detected.The filtered blood serum weredetected by the DRG(Germany, IgG/IgM/IgA) Lp kit and R&D (USA,IgG、IgM、 IgA) Lp kit too. And then compare to evaluate the feasibility of differentmethods by the sensitivity of the method, specificity and consistency of the testresults of the kit.Results： The recombinant MIP protein was successfully expressed andpurified with Mr being40000in E.coli BL21.The purified MIP protein was thecoating antigen to develop an indirect ELISA.The Lp antibody IgG,IgM and IgAin blood serum were detected,respectively. Compared with DRG(Germany,IgG/IgM/IgA) Lp kit, the specificity was90.9%and the sensitivity was92.8%, theKappa value was0.837(P＜0.05), the area of under the ROC curve was0.911;Then compared with R&D Lp kit, the specificity of IgG was88.5%and thesensitivity was95.5%, the Kappa value was0.846(P＜0.05), the area of under theROC curve was0.927; the specificity of IgM was89.3%and the sensitivity was97.6%, the Kappa value was0.88(P＜0.05), the area of under the ROC curve was 0.947;the specificity of IgA was90%and the sensitivity was95%, the Kappavalue was0.854(P＜0.05), the area of under the ROC curve was0.929.Conclusion: Successfully achieve Legionella pneumophila MIP proteinsstability expression and purification, then use of the MIP protein as coatingantigen in the Legionella pneumonia serological diagnostic,this method has greatdiagnostic value.