ELISA method for detecting anti-Echinostoma caproni (Trematoda: Echinostomatidae) immunoglobulins in experimentally infected ICR mice.

An enzyme-linked immunosorbent assay (ELISA) utilizing surface glycocalyx membrane crude antigen of adult Echinostoma caproni was developed for the detection of circulating anti-E. caproni immunoglobulins in sera from experimentally infected ICR mice. Whole blood, serum, and dried blood on filter paper gave similar results. The latter was selected for convenience. A concentration of 10.0 micrograms/ml of antigen was optimal in terms of specificity, sensitivity, and test speed. It was possible to detect anti-E. caproni immunoglobulins at a dilution of 10(-4.11). Low absorbance values (< 0.050) of nonspecific background were observed. In a blind trial the described ELISA accurately differentiated sera taken from infected and uninfected mice. All experimentally infected mice had ELISA-detectable anti-E. caproni immunoglobulins reactive on day 8 postinfection (PI) with the surface glycocalyx antigen. The antibody level varied widely over a 40-day period showing a characteristic and consistent pattern. Mice developed antibodies to E. caproni rapidly, with antibody levels rising by day 8 PI and peaking 6-10 days later. Experimentally infected mice showed time-dependent changes in antibody levels. The proposed ELISA is fast, easy to perform, reproducible, and requires a minimal amount of equipment to collect blood samples. The assay can be used for the detection of anti-E. caproni immunoglobulins in experimentally infected mice, along with monitoring antibody levels in selected groups of mice or for surveys of laboratory experiments where evidence of infection is required.