[Study on diagnosis of schistosomiasis by ELISA using periodate-treated soluble egg antigen].

OBJECTIVE: To improve SEA-ELISA, an immunodiagnostic assay for schistosomiasis. METHODS: Soluble egg antigen (SEA) of Schistosoma japonicum was treated with sodium periodate (SP) in order to oxidate its glycosylated epitopes. ELISA using the treated SEA was then performed to detect specific antibodies to SEA in the sera of schistosomiasis patients. RESULTS: Serum samples were tested by ELISA using SEA treated with sodium periodate (SP-SEA-ELISA), including 64 sera from cases with chronic schistosomiasis japonica, 119 sera from normal individuals in non-endemic area, 34 sera from patients with clonorchiasis, 33 sera of paragonimiasis cases and 36 sera from patients with cysticercosis. The results showed that its sensitivity (98.4%) was similar to that of the routine SEA-ELISA (100.0%) (P > 0.05) and the specificity is higher than that of the SEA-ELISA (P < 0.05). SP-SEA-ELISA showed a higher negative rate (89.0%) for sera of schistosomiasis patients 12 months post-treatment than that of the SEA-ELISA (42.1%). CONCLUSION: Use of SP-SEA can increase the specificity of ELISA, reduce cross-reactivity with serum samples from cases infected with other parasites and improve its value in evaluating therapeutic efficacy.

[Fractionation and identification of Schistosoma japonicum adult worm 67kD protein].

OBJECTIVE: To isolate the specific protein bands which react to sera from rabbits infected with Schistosoma japonicum (Sj) and those immunized with Sj adult worm antigens (AWA) for immunodiagnosis of schistosomiasis. METHODS: AWA was analysed using SDS-PAGE and immunoblotting, and 67 kD protein was fractionated by electrophoretic chromatography. RESULTS: 67 kD protein which reacted to rabbit sera infected with Sj and immunized with AWA was obtained after the fractionation of AWA through electrophoretic chromatography. CONCLUSIONS: Electrophoretic chromatography is a useful tool for the fractionation of schistosome antigens.