Do trematode parasites disrupt defence-cell signalling in their snail hosts?

More than a decade ago, it was postulated that components derived from trematode parasites block receptors on the defence cells of their snail intermediate hosts, thus preventing host-cell activation and parasite elimination. This phenomenon has still not been investigated extensively. However, recent work concerning the molecular regulation of the molluscan defence response provides a new framework for studies that focus on an extension of this original concept – subversion of host cell signalling by trematode parasites. The hypothesis is that, to facilitate survival and replication in their intermediate hosts, trematode parasites downregulate host defence responses by interfering with key signal-transduction pathways in snail defence cells.