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.
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.
Stadelmann
Britta
B
Institute of Parasitology, Vetsuisse Faculty, University of Berne, Länggass-Strasse 122, CH-3012 Berne, Switzerland.
Scholl
Sabrina
S
Müller
Joachim
J
Hemphill
Andrew
A
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
D000871:Anthelmintics; D003470:Culture Media; D015801:Helminth Proteins; D013844:Thiazoles; D005956:Glucose-6-Phosphate Isomerase