Immunoassay Developed for Human Fasciolosis

A lateral flow immunoassay (LFIA) has been developed and evaluated for the serodiagnosis of human fascioliasis caused by the liver fluke.

The test was constructed with a recombinant cathepsin L1 from Fasciola hepatica, and uses protein A and a monoclonal antibody as detector reagents in the test and control lines, respectively.

Scientists at the Universidad de Santiago de Compostela (Spain) developed a rapid, simple and inexpensive immunochromatographic method for the diagnosis of F. hepatica and compared it with an enzyme linked immunosorbent assay (ELISA). They analyzed serum samples from 39 patients with fascioliasis, 27 patients with schistosomiasis, 20 patients with filariasis, nine patients with hydatid disease, 15 patients with anisakiosis, 22 patients with toxocariasis, 12 patients with Chagas' disease, and sera from 59 patients with noninfectious pathology.

The results obtained from the lateral flow immunoassay, called the SeroFluke, test were compared with the MM3-SERO ELISA test, using sera from patients positive for fascioliasis and sera from patients with the other parasitic infections The MM3-SERO ELISA is a capture immunoassay that detects antibodies against the highly specific antigens recognized by monoclonal antibody MM3. There was an almost perfect concordance of results obtained by both methods, for 39 positive and 164 negative samples. The only partial discrepancy was one serum sample containing a very small amount of anti-Fasciola antibodies, which tested doubtful (Optical density (OD) = 0.08) in the MM3-SERO ELISA and positive in the SeroFluke test.

The mean value for the MM3-SERO ELISA in the group of Fasciola positive sera was an OD of 1.61 (OD range: 0.08–2.71), all of which produced a clear signal in the test line of the SeroFluke device. Although some positive sera produced higher signals with SeroFluke than with MM3-SERO, more than 82% of sera that produced strong signals in the SeroFluke test also produced good signals in ELISA.

The authors conclude that the SeroFluke test was a highly stable, sensitive, and specific LFIA for serodiagnosis of human fascioliasis. It is expected that such a test will be useful for hospitals in hypoendemic regions as well as in hyperendemic regions where point-of-care testing is required. Overall, it is considered that between 2.4 million and 17 million people from 55 countries are infected by Fasciola species, and that 180 million people are at risk of infection. It is expected that this trematode-induced disease will increase over time as a result of climate change and the advent of milder, wetter weather. The study was published on November 8, 2011, in the journal Public Library of Science Neglected Tropical Disease.

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Universidad de Santiago de Compostela