Using recombinant Chlamydia trachomatis OMP2 as antigen in diagnostic ELISA test

Background and Objectives: The obligate intracellular bacterium Chlamydia trachomatis causes sexually transmissible diseases in human. Timely and sensitive detection of this pathogen is very important. There are many cross-reactions in bacteriological and serological methods in detection of this type of pathogens. The aim of this study was to achieve a more specific antigen for serological tests. Materials and Methods: Blood samples were taken from 192 women with suspected chlamydial infection and sera were isolated. ELISA plate wells were coated with recombinant C. trachomatis OMP2 as antigen. Cut-off system was determined with 40 negative sera. The final results of this research were compared with Euroimmun commercial kit. Results: The ELISA system cut-off was calculated at 0.27 using negative sera samples. ODs of positive samples were higher than 0.27 and negative samples were lower than it. We obtained 30 samples (15.62%) as positive and 162 cases (84.37%) as negative. Sensitivity and specificity of the recombinant antigen were 90% and 86%, respectively. This antigen showed no cross-reactivity with sera of patients infected with Hydatid cyst, HCV, Epstein barr virus, HBV, Helicobacter pylori, Toxo- plasma gondii, Cytomegalovirus, Mycoplasma, Measles and Varicella zoster virus. Conclusion: The sensitivity and specificity of rOMP2 in ELISA for detection of C. trachomatis were 90% and 86%, respec- tively. Though the sensitivity was higher than results of Euroimmun commercial kit, its specificity was calculated lower than reference kit.