Recombinant Expression And Application Of Ornithine Aminotransferase (SjOAT) And Immunophilin (sjIP) Screened From Schistosoma Japonicum Worm Based-on Proteomics For The Diagnosis Of Schistosomiasis

ObjectiveExploration of sensitive and specific diagnostic antigen has become a focus of the study on immune diagnostic techniques of S.japonica. We used the techniques of two dimensional electrophoresis combined with immunoblotting assay and to analyze the soluble components of the adult worm antigens of Schistosoma japonicum. Ornithine aminotransferase (SjOAT) and Immunophilin(SjIP) were screened, expressed and evaluated on the immunological diagnosis of S.japonica.MethodsThe plasmid pET28a/SjOAT and pET28a/SjIP were constructed and transformed into E.coli BL21. The recombinant proteins were expressed following induction with IPTG. The fusion protein were purified by Ni²⁺-NTA chromatography and identified by SDS-PAGE and Western blotting. The sensitivity and specificity of the recombinant SjOAT and SjIP used in ELISA (rSj-ELISA) were compared in parallel with the commonly used soluble egg antigen (SEA-ELISA).ResultsThe plasmid pET28a/SjOAT and pET28a/SjIP were constructed successfully and the fusion proteins were expressed in E. coli. Western blotting confirmed the immunorection of SjOAT and SjIP with the positive sera of patients. Both of them were further applied in the diagnosis of human schistosomiasis japonica using ELISA. The ELISA results revealed sensitivities of 90.4% and 86.4% for acute and chronic schistosomiasis with rSjOAT and 88.5% and 79.0% with rSjIP. Statistical analysis revealed no significant difference in sensitivity (P>0.05) between both recombinant antigen and SEA. For specific comparison, 94 sera from normal control and 94 sera of people in endemic area with negative eggs in the feces were subjected to the detection with rSj-ELISA and SEA-ELISA. Statistical analysis revealed significant difference in specificity between both recombinant antigen and SEA(P<0.05). rSj-ELISA and SEA-ELISA were used to detect the sera of patients with clonorchiasis, paragonimiasis and hookworm infection. Statistical analysis revealed no significant difference in cross-reactivity between both recombinant antigen and SEA(P>0.05).ConclusionSjOAT and SjIP were successfully expressed. Our present study confirmed that both rSjOATand rSjIP were promising antigens for serological diagnosis of S.japonica.