DOT IMMUNOASSAY WITH BIOTINYLATED ANTIGEN FOR DETERMINATION OF ANTIBODIES AGAINST THE CIRCULATING CATHODIC ANTIGEN (CCA) IN SCHISTOSOMIASIS-JAPONICA

Based on the fact that schistosomiasis patients in both the acute and chronic phase of the infection show a strong humoral immune response a gainst the gut-associated circulating cathodic antigen, a simple and s ensitive dot immunobinding assay for schistosomiasis japonica was deve loped. Circulating cathodic antigen that had been purified by immunoad sorption using monoclonal antibody was biotinylated with biotin aminoc aproylhydrazide via the carbohydrate moiety of the antigen. Serum samp les dotted onto nitrocellulose strips were then tested in an assay inv olving a combined incubation step of biotinylated antigen and streptav idin peroxidase, and a subsequent staining; the total assay time was 1 .5 hr. Assaying the sera of 105 uninfected controls and 104 Schistosom a japonicum-infected individuals showed a specificity of 99.0%, and se nsitivities of 96.2% (acute infections) and 94.1% (chronic infections) . The described assay is economic, rapid, and reproducible and lends i tself to use under field conditions.