The role of evolutionarily conserved signalling systems in Echinococcus multilocularis development and host-parasite interaction.

Alveolar echinococcosis, one of the most serious and life-threatening zoonoses in the world, is caused by the metacestode larval stage of the fox-tapeworm Echinococcus multilocularis. Mostly due to its accessibility to in vitro cultivation, this parasite has recently evolved into an experimental model system to study larval cestode development and associated host-parasite interaction mechanisms. Respective advances include the establishment of axenic in vitro cultivation systems for parasite larvae as well as culture systems by which the early development of metacestode vesicles from totipotent parasite stem cells can be reconstituted under controlled laboratory conditions. A series of evolutionarily conserved signalling molecules of the insulin, epidermal growth factor and transforming growth factor-beta pathways that are able to functionally interact with corresponding host cytokines have been described in E. multilocularis and most likely play a crucial role in parasite development within the liver of the intermediate host. Furthermore, a whole genome sequencing project has been initiated by which a comprehensive picture on E. multilocularis cell-cell communication systems will be available in due time, including information on parasite cytokines that are secreted towards host tissue and thus might affect the immune response. In this article, an overview of our current picture on Echinococcus signalling systems will be given, and the potential to exploit these pathways as targets for anti-parasitic chemotherapy will be discussed.