SURFACE AND ES ANTIGENS OF ADULT DICROCOELIUM-DENDRITICUM INDUCING BILE ANTIBODY-RESPONSES IN NATURALLY INFECTED CATTLE

Bile antibody responses of naturally infected cattle to surface and ES protein antigens of adult D. dendriticum were analysed. Freshly isola ted and carefully purified flukes were surface labelled with NHS-bioti n or biotin hydrazide (BH) and extracted using Tris-buffered saline. B iotinylated surface proteins or glycoproteins were then isolated by st reptavidin affinity chromatography. ES products were obtained during 2 4 h incubation of undamaged worms at 37 degrees C in Tyrode's salts so lution enriched with antibiotics. Bile samples were collected at slaug hter from cattle harbouring 120-280 lancet flukes. The fluke antigens inducing bile antibody responses were analysed by SDS-PAGE, Western bl ot and ELISA techniques. Bile from non-infected cattle precipitated no ne 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 immunocompl exes formed by bile and surface extracts of flukes labelled with BH co ntained 2-5 fluke glycoproteins. An average of 3 polypeptides were rec ognised in ES products. In ELISA tests 38-67% out of 150 samples react ed with ES antigens while 70% possessed antibodies against surface pro teins and 92% against surface glycoproteins. It is suggested that the surface and ES antigens may be of particular importance in the host-pa rasite relationship.