THE ULTRASTRUCTURAL-LOCALIZATION OF ECHINOCOCCUS-GRANULOSUS ANTIGEN-5

Murine monoclonal and polyclonal antisera, raised against the 38 kDa s ubunit of Echinococcus granulosus antigen 5, were used to investigate the tissue distribution of the antigen in hydatid cysts. Immunoreactiv ity was visualized by indirect immunofluorescence on whole protoscolec es, and ultrastructural immunocytochemistry utilizing colloidal gold-b ased labelling procedures on unsectioned and cryosectioned brood capsu les and protoscoleces. In protoscoleces, the 38 kDa subunit of antigen 5 was localized at the interface of parenchymal cells and associated extracellular matrices, as well as along the interface of the tegument ary syncytium in the somal region and its basal matrix. Cytoplasmic la belling of parenchymal cells was rare; when observed, it was associate d with vesicles and membranes in cytoplasmic extensions of parenchymal cells. In brood capsules, the antigen was associated with the externa l face of the plasma of degenerating parenchymal cells. The 38 kDa sub unit occurs along the extracellular face of cell membranes, suggesting that antigen 5 is either a component of the membranes or associated e xtracellular matrices.