Changing surface antigen and carbohydrate patterns during the development of Oesophagostomum dentatum

Living and fixed specimen of Oesophagostomum dentatum were labelled in situ with serum antibodies or a panel of biotin-labelled lectins. Specific bind ing of antibodies was observed in all parasitic stages - freshly exsheathed 3rd-stage larvae (L3), 3rd- and 4th-stage (L4) larvae cultured in vitro an d L3 and L4 and adults isolated from pig intestines. The shedding of the st ained layer by motile larvae was inhibited by levamisole-induced paralysis. Larvae cultured in vitro exposed serum-derived proteins on their surface w hich could be labelled with secondary antibody directed against the respect ive serum donor species. While freshly exsheathed larvae were recognized by O. dentatum-positive serum only, older larvae and adults cross-reacted wit h serum from pigs infected with O. quadrispinulatum, a closely related spec ies. Lectin binding varied considerably between stages. While binding was n ot observed in pre-parasitic stages, Concanavalin A, Soybean Agglutinin, Wh eat Germ Agglutinin, Ricinus communis Agglutinin and Peanut Agglutinin boun d to developing larvae in varying degrees. Dolichos biflorus Agglutinin onl y bound to advanced (luminal) larval stages, while adults generally display ed only weak or partial lectin binding (except with Concanavalin A and Whea t Germ Agglutinin). Ulex europaeus Agglutinin only labelled larvae derived from cultures containing 10% pig serum. Cleavage of the carbohydrate residu es by sodium periodate treatment resulted in reduction of antibody binding to cultured larvae, but not to freshly exsheathed L3. Concanavalin A, Soybe an Agglutinin, and Peanut Agglutinin binding was also reduced by periodate treatment, while binding of Wheat Germ Agglutinin and Ricinus communis Aggl utinin was inhibited only in early L3, but not in older stages. The differe nt lectin labelling patterns are related to the different stages of the nem atode - infective, invasive, histotropic, and luminal - and may serve as a mode of adaptation for the parasite against the host's immune attack by sur face glycoprotein variation, together with antigen shedding (as demonstrate d by labelling of motile larvae) and a possible acquisition of host molecul es at the parasite's surface. Furthermore, a possible role of this developm ental variation in surface carbohydrates in parasite-parasite interactions is discussed.