Biochemical characterization of surface antigens of infective larvae and adults of Haemonchus contortus

Surface proteins of the nematode Haemonchus contortus were biochemically characterized and their antigenic properties were investigated. Living parasites were labelled with NHS-biotin. Next, extracts were made using cetyltrimethylammonium bromide (СТАВ), Tris buffered saline (TBS), sodium dodecyl sulphate (SDS) and 2-mercaptoethanol (BME) as solubilizing agents. The presence of glycoproteins in the extracts was examined by probing Western blots with the lectin Concanavalin A (Con A). The antigenic character of the surface proteins was studied by immunoblotting. Glycosylated polypeptides constituted the major part of the surface molecules of larvae, whereas the proportion of glycoproteins in adults is relatively smaller. Surface biotinylation of intact nematodes revealed that СТАВ-, TBS- and SDS-soluble proteins belong to the epicuticle of larvae. СТАВ- and TBS-soluble proteins are present in the surface of adult worms. Many surface proteins of H. contortus were recognized by hyperimmune sera. It was found that the majority of these antigens possess carbohydrate epitopes. However, antigens with nonsugar epitopes are also present in the epicuticle.