Evaluation of a diagnostic monoclonal antibody-based capture enzyme-linked immunosorbent assay for detection of a 26- to 28-kd Fasciola hepatica coproantigen in cattle.

OBJECTIVE: To develop a monoclonal antibody-based capture ELISA for detection of a 26- to 28-kd coproantigen of Fasciola hepatica in the feces of infected cattle. ANIMALS: 27 crossbred yearling calves, 2 New Zealand White rabbits. PROCEDURE: A capture ELISA that uses a previously described monoclonal antibody (MAB) M2D5/D5F10 was developed. The MAB was used to capture the antigen from the feces, and hyperimmune rabbit serum raised against the purified 26- to 28-kd glycoprotein was used to detect the coproantigen. This test was used for the detection of the antigen in the feces of 27 experimentally infected calves with known numbers of flukes. Fecal specimens obtained before infection from the same calves were used as negative controls.
RESULTS: The assay results identified all calves infected with more than 10 flukes at necropsy, and as little as 300 pg of coproantigen/ml of fecal supernatant was detected. The assay results correlated well with the number of flukes, suggesting that it is possible to estimate fluke burden. Infections as early as 6 weeks duration were detected, before flukes mature to adults and start to shed eggs.
CONCLUSIONS: In experimentally infected calves, the coproantigen capture ELISA was more sensitive and easier to perform than microscopic examination for the diagnosis of F hepatica infection; moreover, 6-week-old prepatent infections were detectable. CLINICAL RELEVANCE: This capture ELISA containing an F hepatica 26- to 28-kd coproantigen is a quantitative assay that is more sensitive than fecal egg counting. In addition, the assay is rapid, easy to perform and lends itself well to large numbers of samples. Because it is antigen based, the ELISA may be useful for diagnosis of F hepatica infection in other species, including human beings.