Echinococcus multilocularis: the parasite-host interplay.

Alveolar echinococcosis (AE) is a severe chronic helminthic disease caused by the intrahepatic tumor-like growth of the metacestode of Echinococcus multilocularis. Metacestodes are fluid-filled, asexually proliferating vesicles, which are entirely covered by the laminated layer, an acellular carbohydrate-rich surface structure that protects the parasite from immunological and physiological reactions on part of the host. The E. multilocularis metacestode has acquired specific means of manipulating and using the immunological host response to its own advantage. These include the expression of distinct immunoregulatory parasite molecules that manipulate and interfere in the functional activity of macrophages and T cells. Recent research findings have led to a better understanding of the protein- and glycoprotein composition of the laminated layer and the E/S fraction of the metacestode, including Em2- and Em492-antigens, two metacestode antigen fractions that exhibit immunosuppressive or -modulatory properties. Understanding of the events taking place at the host-parasite interface is the key for development of novel immuno-therapeutical and/or chemotherapeutical tools.