title: Application of an in vitro drug screening assay based on the release of phosphoglucose isomerase to determine the structure-activity relationship of thiazolides against Echinococcus multilocularis metacestodes.
abstract: OBJECTIVE
  The disease alveolar echinococcosis (AE), caused by the larval stage of the cestode Echinococcus multilocularis, is fatal if treatment is unsuccessful. Current treatment options are, at best, parasitostatic, and involve taking benzimidazoles (albendazole, mebendazole) for the whole of a patient's life. In conjunction with the recent development of optimized procedures for E. multilocularis metacestode cultivation, we aimed to develop a rapid and reliable drug screening test, which enables efficient screening of a large number of compounds in a relatively short time frame.
  
  
  METHODS
  Metacestodes were treated in vitro with albendazole, the nitro-thiazole nitazoxanide and 29 nitazoxanide derivatives. The resulting leakage of phosphoglucose isomerase (PGI) activity into the medium supernatant was measured and provided an indication of compound efficacy.
  
  
  RESULTS
  We show that upon in vitro culture of E. multilocularis metacestodes in the presence of active drugs such as albendazole, the nitro-thiazole nitazoxanide and 30 different nitazoxanide derivatives, the activity of PGI in culture supernatants increased. The increase in PGI activity correlated with the progressive degeneration and destruction of metacestode tissue in a time- and concentration-dependent manner, which allowed us to perform a structure-activity relationship analysis on the thiazolide compounds used in this study.
  
  
  CONCLUSIONS
  The assay presented here is inexpensive, rapid, can be used in 24- and 96-well formats and will serve as an ideal tool for first-round in vitro tests on the efficacy of large numbers of antiparasitic compounds.
authors.affiliation: Institute of Parasitology, Vetsuisse Faculty, University of Berne, Länggass-Strasse 122, CH-3012 Berne, Switzerland.
authors.forename: Britta
authors.initials: B
authors.lastname: Stadelmann
authors.forename: Sabrina
authors.initials: S
authors.lastname: Scholl
authors.forename: Joachim
authors.initials: J
authors.lastname: Müller
authors.forename: Andrew
authors.initials: A
authors.lastname: Hemphill
mesh_terms: D000818:Animals; D000871:Anthelmintics / Q000494:pharmacology*; D003470:Culture Media / Q000737:chemistry*; D004353:Drug Evaluation, Preclinical / Q000191:economics / Q000379:methods*; D048210:Echinococcus multilocularis / Q000187:drug effects*; D005956:Glucose-6-Phosphate Isomerase / Q000032:analysis*; D015801:Helminth Proteins / Q000032:analysis*; D006801:Humans; D013329:Structure-Activity Relationship; D013844:Thiazoles / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D000871:Anthelmintics; D003470:Culture Media; D015801:Helminth Proteins; D013844:Thiazoles; D005956:Glucose-6-Phosphate Isomerase