Effects of different Fasciola hepatica recombinant proteins on the biochemical and serological responses of experimentally infected sheep

In the DELIVER (Full project title: Design of effective and sustainable control strategies for liver fluke in Europe) project the objective was to analyze 3 recombinant antigens for their capacity to induce a satisfied immune response in sheep, to challenge the animals with metacercariae of Fasciola hepatica, and to observe their immune response and protection from the parasitosis. The animals were treated initially with metacercariae and every second week blood was taken for liver enzyme estimation of lactate dehydrogenase (LDH), gamma-glutamyl transferase (gamma GT), and antibody response. After the 3rd month of infection all the animals developed parasitosis, although to different extents. Differential observations of the blood showed a rise in eosinophils after the 3rd month (typical by parasitoses) and specific reactions of the other white blood cells. The LDH and gamma GT liver enzymes showed a slight fluctuation in comparison with the initial values. The antibody (immunoglobulin G1) formations against the different antigens (made by enzyme-linked immunosorbent assay) were typical as well, but not strong enough to protect the animals from the disease. The immune response was mostly pronounced against the cathepsin L1 antigen, with the highest values after 5-6 months. It turned out that the chosen adjuvant was successful too, because of the high response to it alone. The differential count of the blood cells showed a rise in the eosinophils. The liver enzymes were not typical for this disease. The results gave strong suggestions of how to operate further and what kind of corrections should be made.