Echinococcus multilocularis: molecular and immunochemical characterization of diagnostic antigen II/3-10

Abstract

SummaryA recombinantEchinococcus multilocularisantigen (II/3–10), which had previously been shown to exhibit immunodiagnostic characteristics highly specific for human alveolar echinococcosis, and the corresponding native parasite antigen, were further characterized with immunochemical and molecular biological methods. Immunoblot analysis using a polyclonal antiserum raised in rabbits against the recombinant protein, and subsequent Northern hybridization analysis, revealed that the native antigen was expressed byE. multilocularisat the adult as well as at the metacestode stage. In metacestodes, the antigen was shown by using indirect immunofluorescence and the same antiserum to be localized within the germinal layer and membrane structures of developing protoscolices. Electrophoretic analyses revealed remarkable differences in the apparent molecular weight of the antigen under reducing and non-reducing conditions. In further immunoblot analyses, anti-II/3–10 antibodies identified the corresponding epitopes on bands with identicalMrin allE. multilocularisisolates investigated (European, Asian and North American). By Southern hybridization analyses of the respective gene, phylogenetically related sequences were shown to be present in other helminth species such asE. granulosusand severalTaeniaspp. In the same respect, immunoblotting revealed that anti-II/3–10 antibodies reacted with antigens of differentMrfrom variousE. granulosusisolates and some other cestode species, indicating the presence of shared and thus potentially cross-reacting epitopes. The relevance of these findings for the immunodiagnostic performance of the recombinant antigen is discussed.