Comparison of three different novel Chlamydophila pneumonia recombinant antigens for serodiagnosis

Abstract

Objective To evaluate three different Chlamydophila pneumoniae recombinant antigens for use in Chlamydophila pneumoniae serodiagnosis. Methods The recombinant plasmids pGEX6p-2/ Cpn0146,Cpn0147 and Cpn0308 were constructed and expressed as GST fusion proteins. The immunogenicity and the immunocompetence of these recombinant protein were analyzed by Western-blot and indirect ELISA. A total of 183 sera samples of patients with respiratory tract infection and 32 sera samples of patients with Chlamydia trachomatis infection were detected with indirect ELISA coated microwell plates with the purified recombinant proteins comparing with SeroCP-TM IgG ELISA kits. The positive recognition rate, sensitivity and specificity of each method were analyzed. Results GST-Cpn0146, Cpn0147 and Cpn0308 were obtained after expression and purification. The titers of the specific IgG antibodies against Cpn0146, Cpn0147 and Cpn0308 were higher than 1:6 400, 1:128 00 and 1:128 00, respectively. When the indirect ELISA was developed to detect the IgG antibody against Chlamydophila pneumoniae in 183 samples, the concordance rate between the indirect ELISA test and SeroCP-TM IgG ELISA kits were 92. 3% (Cpn0146) , 94.5% (Cpn0147) and 96.7% (Cpn0308), respectively. The recombinant Cpn0146, Cpn0147 and Cpn0308 were recognized by 71 (38.8% positive recognition rate), 75 (40.9%), and 82 (44.8%) samples, respectively. The recombinant antigen-based detection assays displayed > 97% of detection specificity and>87%of sensitivity.Condusion GST-Cpn0308 shows a better sensitivity and specificity,which suggests it could be used for developing serodiagnosis kits of Chlamydophila pneumoniae infection. Key words: Chlamydophila pneumoniae; Antigens,bacterial; Recombinant proteins; Serologic tests