ABSTRACT
Objective To optimize the conditions of the expression of fusion protein GST-SjMP10 and to evaluate the value of fusion protein GST-SjMP10 for diagnosis of schistosomiasis.Methods The optimal concentration of IPTG for the expression of fusion protein GST-SjMP10 was chosen in inducing the expression of GST-SjMP10 with different concentration of IPTG,and the soluble fusion protein GST-SjMP10 was identified by SDS-PAGE.The fusion protein GST-SjMP10 was purified by chromatographic affinity with glutathione Sepharose 4B gel.The sensitivity and specificity of purified fusion protein GST-SjMP10 for diagnosis of schistosomiasis were determined by enzyme linked immunosorbent assay(ELISA)to detect the IgG antibody in sera from the patients with acute schistosomiasis,advanced schistosomiasis and clonorchiasis as well as healthy subjects.Results Most of the expressed fusion protein GST-SjMP10 was in soluble status when the concentration of IPTG was reduced to 0.1 mmol/L and the fusion protein GST-SjMP10 could be purified by chromatographic affinity.The positive rate of anti-GST-SjMP10 antibody in the sera from the patients with acute and chronic schistosomiasis japonica was 97.5% and 96.7% respectively.No cross reactivity of the fusion protein GST-SjMP10 was found in the detection for the sera from clonorchiasis patients,and no false positive was found in the detection for the sera of healthy subjects.Conclusion The fusion protein GST-SjMP10 was expressed successfully and showed high sensitivity and specificity for the diagnosis of schistosomiasis japonicum.
ABSTRACT
Objectives To express the miracidial antigen from eggs of Schistosoma japonicum (Chinese mainland strain) (SjMP10), and investigate the role of the miracidial antigen during the hepatic granuloma formation of schistosomiasis. Methods A pair of specific primers was designed and synthesized according to the nucleotide sequence of the open reading frame of the miracidial antigen gene. The open reading frame of the miracidial antigen gene was amplified, digested by restrictive enzyme(BamHI, SalI), and cloned directly into the expression plasmid pGEX-4T-3 to construct the recombinant plasmid. The recombinant plasmids were transformed into E. coli BL21(DE3), and induced by IPTG to express the fusion protein of GST-SjMP10. The expressed fusion protein was purified by electric elution method, and its antigenicity was examined by Western blotting and lymphocyte proliferation test. Results The gene of miracidial antigen was cloned into the expression plasmid pGEX-4T-3. After induced by IPTG, the recombinant expressed a fusion protein of GST-SjMP10, with a molecular weight of 39 000 approximately. The purified fusion protein showed proper antigenicity that could be recognized by the sera of rabbits heavily infected by Schistosoma japonicum and could stimulate the proliferation of splenic lymphocytes of infected BALB/c mice. Conclusion The miracidial antigen from eggs of Schistosoma japonicum was expressed successfully.