ECHINOCOCCUS-MULTILOCULARIS - MOLECULAR AND IMMUNOCHEMICAL CHARACTERIZATION OF DIAGNOSTIC ANTIGEN II 3-10/

A recombinant Echinococcus multilocularis antigen (II/3-10), which had previously been shown to exhibit immunodiagnostic characteristics hig hly specific for human alveolar echinococcosis, and the corresponding native parasite antigen, were further characterized with immunochemica l and molecular biological methods. Immunoblot analysis using a polycl onal antiserum raised in rabbits against the recombinant protein, and subsequent Northern hybridization analysis, revealed that the native a ntigen was expressed by E. multilocularis at the adult as well as at t he metacestode stage. In metacestodes, the antigen was shown by using indirect immunofluorescence and the same antiserum to be localized wit hin the germinal layer and membrane structures of developing protoscol ices. Electrophoretic analyses revealed remarkable differences in the apparent molecular weight of the antigen under reducing and non-reduci ng conditions. In further immunoblot analyses, anti-II/3-10 antibodies identified the corresponding epitopes on bands with identical M(r) in all E. multilocularis isolates investigated (European, Asian and Nort h American). By Southern hybridization analyses of the respective gene , phylogenetically related sequences were shown to be present in other helminth species such as E. granulosus and several Taenia spp. In the same respect, immunoblotting revealed that anti-II/3-10 antibodies re acted with antigens of different Mr from various E. granulosus isolate s and some other cestode species, indicating the presence of shared an d thus potentially cross-reacting epitopes. The relevance of these fin dings for the immunodiagnostic performance of the recombinant antigen is discussed.