Idiotype anti-idiotype: An experimental schistosomiasis vaccine.

Abstract

Schistosomiasis is a widespread parasitic infection affecting 200 hundred million people in tropical countries. Since most attempts at controlling this parasite have proven unsuccessful, efforts are now being focused on the application of Jerne's network theory (185,186), involving the use of idiotype anti-idiotype methodology. This dissertation presents the characterization of an experimental schistosomiasis vaccine, based on antiidiotypic antibodies (anti-id). Anti-id (AB2) were constructed against human IgG antibodies from pregnant Egyptian mothers chronically infected with Schistosoma haematobium made specific for S. mansoni by passage over a CNBr-Sepharose 4B column (AB1). AB2 antibodies were selected by their capacity to bind to AB1 in an ELISA assay. Balb/c mice vaccinated with anti-id (AB2) in CFA engendered a significant level of protection (26.8%) against a challenge infection with normal S. mansoni cercariae, when compared to sham immunized controls. Sera from naive Balb/c mice immunized with affinity purified AB2 preparations contained a subset of anti-anti-schistosomula antibodies (AB3), which was shown to bind to the surface of live 4 h old mechanically transformed schistosomula by an indirect immunofluorescence assay (IFA), and to schistosomula membrane antigen (SMA) in an ELISA assay. These results indicate that our anti-id constructed, using monoclonal antibody technology can act as a surrogate vaccine against experimental schistisomiaisis. More importantly, our data demonstrated that a specific an anti-schistosomular immune response can be induced in naive animals without ever exposing them to the infectious agent.