In addition, RNAi of either enzyme induced transient, abnormal phenotypes associated with altered movement. The data also suggested that both cathepsin B and L proteases are essential for host (rat) gut penetration and that interference with the function of either of the two enzymes has a severe impact on worm virulence (80). The metacestode Selumetinib clinical trial larval stage of the fox tapeworm Echinococcus multilocularis is the causative agent of alveolar echinococcosis, a serious zoonosis in rodents and

humans (81). Because of its accessibility to in vitro cultivation (82), E. multilocularis has been established as a laboratory model for studying the molecular basis of larval taeniid cestode development and host–parasite interactions.

In this context, it is highly desirable to be able to perform functional genomics studies to investigate the role of defined parasite genes in these processes. The first attempts to establish transfection in Echinococcus were reported by Spiliotis and colleagues (Table 1). A plasmid containing the cyano-fluorescent protein (CFP) under the control of the promoter of the ezrin–radixin–moesin (ERM)-like protein gene (83) was transfected into primary cells using cationic lipid vesicles. Because of the strong autofluorescence of the E. multilocularis cells, the authors were unable to visualize the expression of the reporter gene CFP, but Selleckchem KPT330 the reporter protein could be detected by Western blot several days after transfection (84). In this publication, the use of Listeria monocytogenes as a transfection vehicle was also explored as suicide strains of this facultative intracellular bacterium have already DNA ligase been used to deliver foreign DNA into host cells (85). Here, E. multilocularis metacestode tissue was incubated with L. monocytogenes carrying a plasmid for the expression of GFP after which primary cells were isolated and cultured for several days. The authors were able to detect fluorescent bacteria

close to the nuclei of primary cells, indicating an intracellular location of L. monocytogenes, but have not yet been able to achieve transfer of foreign DNA into Echinococcus cells using this method. Recently, RNAi (Table 2) was also applied successfully in E. multilocularis (86). To establish whether a functioning RNAi pathway is present in Echinococcus, the authors scanned the available E. multilocularis genomic sequences for the presence of dicer and argonaute orthologs. RT-PCR analysis established that both genes were expressed in E. multilocularis primary cell cultures. Subsequent exposure to siRNA facilitated by electroporation, targeting emgapdh, em14-3-3 and ERM-like protein resulted in efficient knock-down to 10–30% of the original transcript levels which remained down-regulated for at least two weeks. This was confirmed by Western blot analysis where levels of the respective proteins were shown to be down-regulated between 70% and 90%.