Expression recombinant major outer membrane protein gene (Sxh56) of Orientia tsutsugamushi Shanxi and application in ELISA
Objective To explore the expression of the 56kD protein of Orientia tsutsugamushi, which is located on the member surface of Orientia. Methods The gene that encodes the 56kD protein of O.tsutsugamushi Shanxi (sxh56) has been amplified by PCR and cloned into an expression vector pQE30. The 56kD protein of Oriental tsutsugamushi Shanxi was expressed as a fusion protein with the 6×His-binding protein of Escherichia coli. The recombinant protein expressed in Escherichia coli M15 as an inclusion body. Recombinant protein only reacted to polyclonal antiserum to Ot. Gilliam and Ot. Sxh951 in ELISA and immunoblot assay. The recombinant protein was used in an enzyme-linked immunosorbent assay to evaluate the method for the detection of the antibody to O.tsutsugamushi in human and animal sera. Results One hundred and fifty-one positive sera and 412 negative human sera to Ot. Gilliam in IFA were detected with the recombinant protein and the sensitivity was 88.08%, specificity was 96.36%. 30 positive sera and 50 negative animal sera to Ot. Gilliam in IFA were also detected with the recombinant protein and the sensitivity and specificity were 100% and 96.67%. Conclusion The purified sxh56 is a suitable candidate of immunodiagnostic antigen.