Development of recombinant OmpA and OmpB proteins as diagnostic antigens for rickettsial disease

• Published in: Microbiology and immunology 2009-07, Vol.53 (7), p.368-374
• Main Authors: Do, Eun-Ju, Kim, Jung-Eun, Park, Jin-Mi, Lee, Kyung-Min, Jung, Mi-Yun, Lee, Haeng-Jung, Cho, Hyun-Woo, Choi, Yeon-Joo, Lee, Seung-Hyun, Park, Kyung-Hee, Jang, Won-Jong
• Format: Article
• Language: English
• Subjects: Antibodies, Bacterial - blood; Antigens, Bacterial - genetics; Antigens, Bacterial - immunology; Bacterial Outer Membrane Proteins - genetics; Bacterial Outer Membrane Proteins - immunology; ELISA; Enzyme-Linked Immunosorbent Assay; Humans; OmpA; OmpB; recombinant antigen; Recombinant Proteins - genetics; Rickettsia conorii - immunology; Rickettsia Infections - diagnosis; Rickettsia Infections - microbiology; rickettsial disease; Sensitivity and Specificity
• ISSN: 0385-5600; 1348-0421
• DOI: 10.1111/j.1348-0421.2009.00142.x

ABSTRACT In this study the diagnostic potential of Rickettsia conorii recombinant antigens was analyzed. For this, site‐specific PCR primers were used to clone the OmpA and OmpB genes of R. conorii into pMAL‐c2X plasmids. Six fragments of OmpA and four of OmpB were expressed as fusion proteins with maltose‐binding protein in Escherichia coli. OmpA1350‐1784, OmpB801‐1269, and OmpB1227‐1634 regions from truncated proteins were selected as diagnostic candidate antigens by ELISA using control sera. ELISA results of three antigens were compared to the results obtained by using a commercial ELISA kit which contained whole OmpA and OmpB antigens from R. conorii. For this analysis, 40 serum samples taken from febrile patients and uninfected controls were tested. Of the 20 R. conorii test results which were positive with the commercial kit, 18 were shown to be positive by ELISA using OmpA1350‐1784 (a sensitivity of 90%). The specificity of the ELISA was 100%; all of the 20 samples shown to be negative using the commercial kit were also negative in our assay. The sensitivities of the ELISA using the OmpB801‐1269 and OmpB1227‐1634 were 90% and 95%, respectively. The specificities of the OmpB801‐1269 and the OmpB1227‐1634 were 100% and 95%, respectively. These results suggest that specific regions of OmpA and OmpB effectively detect antibodies against R. conorii, and the truncated recombinant antigens could be used for development of diagnostic tools for rickettsial disease.