Development of ELISAs for the detection of urogenital chlamydia trachomatis infection targeting the pORF5 protein / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To prepare antibodies against pORF5 plasmid protein of Chlamydia trachomatis and develop double-antibody sandwich enzyme-linked immunosorbent assays (DAS-ELISAs) for the detection of genital C. trachomatis infections.</p><p><b>METHODS</b>The pORF5 protein was expressed in Escherichia coli and used to immunize BALB/c mice and New Zealand rabbits to produce monoclonal antibodies (mAbs) and polyclonal antibody (pAb) for DAS-ELISAs. Clinical samples from 186 urogenital infection patients (groups I) and 62 healthy donors (groups II) were detected in parallel by the DAS-ELISAs developed in this study and by IDEIA PCE commercial ELISA.</p><p><b>RESULTS</b>Two hybridoma cell lines, named 2H4 and 4E6, stably secreting specific mAbs against pORF5 were obtained. The mAb 2H4 was recognized by 32 (17.20%, positive recognition rate) and 25 (13.44%), mAb 2H4 by 0 (0%) and 2 (3.22%) samples from groups I and II, respectively. The sensitivities of mAbs 2H4 and 4E6 were 92.11% and 77.78% and the specificities were 100% and 96.88%, respectively in relation to the IDEIA PCE commercial ELISA. The sensitivities of detection for the DAS-ELISAs were 10 ng/mL (based on 2H4) and 18 ng/mL (based on 4E6).</p><p><b>CONCLUSION</b>Two DAS-ELISAs were developed in this study that provided a feasible and effective assay that could be considered alternative tools for the serodiagnosis of C. trachomatis infection.</p>

Cloning and cellular localization of pORF8 plasmid protein of Chlamydia trachomatis / 南方医科大学学报

<p><b>OBJECTIVE</b>To clone the plasmid protein pORF8 of Chlamydia trachomatis and localize its expression in Chlamydia-infected cells.</p><p><b>METHODS</b>pORF8 gene was amplified and cloned into pGEX-6p vector, and the pORF8 fusion protein was expressed in E.coli XL1 Blue. After purification with glutathione-conjugated agarose beads, the pORF8 fusion protein was used to immunize BALB/c mice to generate polyclonal antibodies against pORF8 protein. The antibodies obtained were used to localize the plasmid protein pORF8 in Chlamydia-infected cells with immunofluorescence assay (IFA).</p><p><b>RESULTS</b>The pORF8 gene 744 bp in length was successfully cloned and the GST fusion protein with a relative molecular mass of 54 000 was obtained. The cellular distribution pattern of the plasmid protein pORF8 was similar to that of the major outer membrane protein (MOMP), a known C. trachomatis inclusion body protein, but not to that of chlamydial protease-like activity factor (CPAF, a secreted protein).</p><p><b>CONCLUSION</b>The plasmid protein pORF8 is localized on the bacterial organism as an inclusion body protein in C. trachomatis-infected cells. The cellular location of pORF8 protein can potentially provide important insights into the pathogenesis of C. trachomatis.</p>

Preparation and identification of monoclonal antibodies against Chlamydia trachomatis Tarp protein / 南方医科大学学报

<p><b>OBJECTIVE</b>To obtain monoclonal antibodies (mAbs) against Chlamydia trachomatis Tarp protein.</p><p><b>METHODS</b>Chlamydia trachomatis serovar D recombinant Tarp fusion protein was cloned and expressed. Balb/c mice were immunized with recombinant Tarp fusion protein, and the spleen cells of the immunized mice were fused with SP2/0 mouse myeloma cells. The hybridoma cell lines secreting mAbs against Tarp protein were screened by an indirect immunofluorescence assay and subcloned by limiting dilution culture. The specificities of these mAbs to Tarp were determined by ELISA, and their isotype and chlamydial species specificity identified by an indirect immunofluorescence assay.</p><p><b>RESULTS</b>Recombinant GST-Tarp fusion protein with a relative molecular mass of about 136 000 was successfully cloned and expressed. Seven hybridoma cell lines stably secreting specific mAbs against Tarp protein were obtained. All the 7 mAbs reacted strongly with Tarp protein but not with other chlamydial proteins. Two mAbs were identified to belong to IgG2a isotype and the other 5 to IgG1 isotype. All the 7 mAbs reacted strongly with chlamydia serovar A, D, and L2, but not with MoPn, 6BC, or AR39.</p><p><b>CONCLUSION</b>The highly specific mAbs against Tarp protein have been obtained to facilitate further study of the structure and function of Chlamydia Tarp protein.</p>

Cloning and expression of Chlamydia trachomatis OmcBc gene and antigenicity analysis of the protein / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the antigenicity of recombinant Chlamydia trachomatis (Ct) OmcBc protein and search for the new target for early diagnosis of Chlamydia infection and Chlamydia vaccine development.</p><p><b>METHODS</b>The C fragment of OmcB encoding the amino acids from T270 to T553 was amplified from Chlamydia serovar D genomic DNA. The pGEX-6p-Ct OmcBc expression plasmid was constructed and transformed into E.coli XL-1blue. The expression of recombinant Ct OmcBc protein was induced by IPTG. Serum samples were collected from 120 patients with urogenital Chlamydia infection. The antiserum samples were collected from 7 New Zealand white rabbits and 5 Balb/C mice immunized subcutaneously and intraperitoneally with Ct serovar D inactivated EB, respectively, and from 9 Balb/C mice intranasally infected with Ct serovar D live EB. The anti-Chlamydia specific antibody were titrated by an immunofluorescence assay (IFA). The reactivity of the recombinant OmcBc protein with all the above antisera was detected by ELISA.</p><p><b>RESULTS</b>The pGEX-6p-Ct OmcBc expression plasmid was successfully constructed. DNA sequencing showed that the inserted OmcBc was about 852 bp, encoding a protein with 284 amino acids. The expression of the recombinant GST-OmcBc was induced by IPTG, producing a fusion protein with a molecular weight of about 57 kD. The titer of the specific antibodies to Chlamydia in all the antisera was high. ELISA results showed strong reactivities of the recombinant GST-OmcBc fusion protein with all the above antisera.</p><p><b>CONCLUSIONS</b>OmcBc protein is an immunodominant protein of Chlamydia. The recombinant GST-OmcBc with strong antigenicity may provide a basis for further study of early diagnosis of chlamydia infection and development of Chlamydia vaccine.</p>