Evaluation of partially purified soluble egg antigens in colloidal gold immunochromatography assay card for rapid detection of anti-Schistosoma japonicum antibodies.

Shistosomiasis is one of the important parasitic diseases in developing countries and especially remains a threat to public health in China. Many immunodiagnostic kits have shown cross-reactions with other parasitic diseases and need large volumes of serum for the tests. In this study, we evaluated partially purified soluble egg antigen (SEA) in a colloidal gold immunochromatography assay (GICA) card kit for rapid detection of anti-Schistosoma japonicum antibodies using 5 microl of serum. Partially purified SEA from S. japonica was purified by Sephacryl S-300 chromatography. The optional reaction system and detection level of GICA using partially purified SEA were established by improving conjugated concentration and formulation of sample buffer and labeled solution. GICA showed 93.7% sensitivity in detecting schistosomiasis patients, 97.6% specificity in healthy population and patients with other parasitic diseases and a Youden's index value of 0.91. Cross-reaction with other parasitic diseases, such as paragonimiasis (1 case) and toxoplasmosis (1 case) is significantly lower compared to using crude SEA. Partially purified SEA in GICA is practical for detection of schistosomiasis in the field as it requires a small volume of serum, has high sensitivity, and has low cross-reaction rate.

[Development and evaluation of colloidal gold immunochromatography assay (GICA) for detection of antibody against Schistosoma japonica in smaller serum].

OBJECTIVE: To develop a rapid colloidal gold immunochromatography assay (GICA) for detection of the antibody to schistosome in 5 microl sera. METHODS: A soluble egg antigen (SEA) from Schistosomajaponica was separated with sephacryl S-300 column to retain the active antigen fractions to the antibody of schistosome. The optional reaction system and detection kit with 5 microl sera were established by improving conjugated concentration and formulas of sample buffer and labeled solution. RESULTS: The sensitivity of detecting schistosomiasis patients whose stool examinations for schistosome eggs were positive was 93.7%, the specificity to health population 97.1%, the cross reaction rate to patients with paragonimiasis 5.6%. The Youden' s index value was 0.91. There was 96.1% crude coincidence of GICA and ELISA in detecting 507 cases of floating population and the Kappa value was 0.81. CONCLUSION: GICA kit is practical for detection of schistosomiasis in the field because of its advantages such as smaller serum needed, the high sensitivity, lower cross reaction rate and spread application for human and animals.