Separation and comparative immunoassay (DASS, ELISA) with antigens from adult Schistosoma mansoni

Antigenic fractions were prepared from adult Schistosoma mansoni by homogenization and solubilization in phosphate buffer, and subsequent separation on Ultrogel AcA-44. The fractions were tested for antigenicity in two immunodiagnostic techniques, the defined antigen substrate spheres (DASS) system, and the enzyme-linked immunosorbent assay (ELISA), using serum from schistosomiasis patients. The results obtained in the two tests correspond to each other. Sera from 25 patients with proven schistosomiasis were tested with ELISA, using the antigen fractions. For all sera tested, the titres obtained, were dependent on the antigen fraction used. However, areas of high antigenicity were different for different sera. Antigens with molecular weight lower than 60,000, gave negative results for about 30% of the sera but those with molecular weight higher than 60,000 gave positive results for all sera. For about 60% of the sera, the sensitivity of ELISA increased when antigens of increasing molecular weight were used. Cross reactions with two other helminth infections occurred mainly with high molecular weight antigens.