EN
Bile antibody responses of naturally infected cattle to surface and ES protein antigens of adult D. dendriticum were analysed. Freshly isolated and carefully purified flukes were surface labelled with NHS- biotin or biotin hydrazide (BH) and extracted using Tris-buffered saline. Biotinylated surface proteins or glycoproteins were then isolated by streptavidin affinity chromatography. ES products were obtained during 24 h incubation of undamaged worms at 37 °C in Tyrode’s salts solution enriched with antibiotics. Bile samples were collected at slaughter from cattle harbouring 120-280 lancet flukes. The fluke antigens inducing bile antibody responses were analysed by SDS-PAGE, Western blot and ELISA techniques. Bile from non-infected cattle precipitated none of the surface proteins and one polypeptide out of ES products. One to 6 polypeptides were found in immunocomplexes formed by individual bile samples of infected cattle and surface proteins while immunocomplexes formed by bile and surface extracts of flukes labelled with BH contained 2-5 fluke glycoproteins. An average of 3 polypeptides were recognised in ES products. In ELISA tests 38-67% out of 150 samples reacted with ES antigens while 70% possessed antibodies against surface proteins and 92% against surface glycoproteins. It is suggested that the surface and ES antigens may be of particular importance in the host-parasite relationship.