Application of indirect ELISA with recombinant signaling protein 14-3-3 of Schistosoma japonicum for the immunodiagnosis of schistosomiasis

To evaluate the recombinant signaling protein 14-3-3 of Schistosoma japonicum(rSj14-3-3) on the immunodiagnosis of schistosomiasis by indirect ELISA,the expression of rSj14-3-3 in E.coli was induced and purified with affinity chromatography,and the coated antigen concentration and sera dilution were optimized.Sera of patients with acute and chronic schistosomiasis and negative control were tested with rSj14-3-3 and adult worm antigen of Schistosoma japonicum(SjAWA) by indirect ELISA and soluble eggs antigen(SEA)-IHA respectively.It was found that the positive rates of indirect ELISA in 51 cases of acute and 49 of chronic schistosomiasis were 98.0 % and 91.8 % using rSj14-3-3,whereas those were 96.1 % and(90.0 %) using SjAWA.The positive rates of SEA-IHA were 98.0 % and 93.9 % in both acute and chronic patients.Two percent of cross-reaction was noted in normal sera tested by rSj14-3-3 antigen and,6.0 % by SjAWA,compared with 2.0 % of false positive in SEA-IHA.There were no statisticaly significant difference of the results among rSj14-3-3,SjAWA,and SEA-IHA(P0.05).Meanwhile 13.3%,20.0% and 16.7% of cross-reaction were observed among rSj14-3-3-ELISA,SjAWA-ELISA and SEA-IHA for detecting the sera of patients with Clonorchis sinensis as well as 8.3%,(12.5)% and 12.5% in the cases of Paragonimus westermani infection and(12.9)%,16.1% and(12.9)% in the cases of hookworm infection.There was no significant difference of cross-reaction in three parasitic infections.The present study showed that the indirect ELISA with rSj14-3-3 antigen had as high sensitivity and specificity as SEA-IHA for diagnosis of schistosomiasis.