Determination of Immunodominant Antigens of Dicrocoelium Dendriticum by Hyperimmune Sera

Abstract

Dicrocoeliasis caused by the small liver fluke Dicrocoelium dendriticum (syn. D.lanceolatum), which live in the bile ducts and gall bladder of wild and domesticated mammals, particularly livestock farming. Parasitological methods are not reliable enough for diagnosis of this trematode infection. In the present study, the sera from rabbits immunized with somatic and excretory-secretory antigens of D.dendriticum were assayed with immunoblot technique. Adult worms were collected from infected livers of sheep at a local abattoir. The excretory-secretory product and somatic antigens were prepared through homogenization and incubation of trematodes, respectively. Polyclonal antibodies were raised in rabbits after inoculation of the two antigens with emulsified Freunds adjuvant followed by booster injection. Comparative study between D.dendriticum antigens and those of Fasciola, cysticercus tenuicollis and hydatid cyst fluids antigens was carried out. SDS-PAGE of antigens was performed and for immunoblotting analysis, hyperimmune sera were obtained from immunized rabbits of case and control groups. Immunoblot analysis of rabbits antisera against somatic and excretory-secretory antigens of D.dendriticum were showed six and four protein bands ranging from 25 to more than 170 and 25 to 70 kDa molecular weights, respectively. However cross-reaction with other specific proteins was observed in Fasciola excretory-secretory, hydatid cyst and cysticercus tenuicollis fluid antigens. The results demonstrated that the 25-27 kDa proteins were strongly recognized by both hyperimmune sera and was common in both somatic and excretory-secretory antigens. According to the results of this study performed with two antigens of D.dendriticum shows that the 25-27 kDa polypeptide as immunodominant protein, could be considered for the immunodiagnosis of dicrocoeliasis and it probably induces protective immunity against Dicrocoelium infection.