A new semi-automated, motility-based screening assay for discovery of compounds with activity against the juvenile stage of Fasciola hepatica
5 affiliations
- 1Institute of Parasitology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
- 2Graduate School for Cellular and Biomedical Sciences (GCB), University of Bern, Bern, Switzerland
- 3Department of Parasitology, Faculty of Pharmacy, University of Valencia, Valencia, Spain
- 4Division of Veterinary Anatomy, Vetsuisse Faculty, University of Bern, Bern, Switzerland
- 5Multidisciplinary Center for Infectious Diseases, University of Bern, Bern, Switzerland
Abstract
Fasciola hepatica is a trematode parasite responsible for fasciolosis, a liver disease that affects humans and livestock worldwide. Together with other food-borne trematode infections, fasciolosis is considered a neglected tropical disease. Further, it imposes substantial agricultural losses due to infections in ruminants. No vaccine is currently available, and control heavily relies on drug treatment, especially with triclabendazole (TCBZ). However, the intensive use of TCBZ over the past four decades has led to increasing rates of treatment failures and the emergence of drug-resistant parasites. Therefore, the identification of new treatment options is an urgent priority. The currently available toolset for drug screening, however, is limited. To address this need, we established a novel, semi-automated, standardized, and objective screening assay based on motility monitoring of newly excysted juveniles using microscopic live imaging. The assay was validated by testing a panel of ten compounds with known anthelmintic properties, amongst them TCBZ (IC50: 1.5 µM) and the new activator of the F. hepatica transient receptor potential melastatin (TRPMPZQ) ion channel, benzamidoquinazolinone (IC50: 1.05 µM). In addition to these two compounds with known activity against F. hepatica, three compounds were identified as particularly promising with a fast onset of action and IC50 values in the nanomolar range: the salicylanilides MMV665807 (IC50: 44 nM), niclosamide (IC50: 32 nM), and its ethanolamine salt, niclosamide ethanolamine (IC50: 9 nM). Complementary live/dead staining revealed that only TCBZ displayed parasiticidal activity, while the other compounds, although leading to parasite paralysis, did not lead to parasite death within 72 hours. Scanning electron microscopy of drug treated parasites did not reveal any significant damage at concentrations corresponding to the IC50s, but strong phenotypes were visible at 20 µM. The presented motility assay provides a robust method for the discovery of novel anthelmintic compounds and facilitates the ongoing effort to combat fasciolosis. Author summary: Fasciola hepatica, the common liver fluke, is a parasitic platyhelminth that infects the liver and biliary ducts of humans and livestock, causing fasciolosis, a Neglected Tropical Disease as defined by the World Health Organization. Triclabendazole is the drug of choice to treat humans and animals. However, its intensive use has led to the emergence of drug resistance resulting in treatment failures worldwide. The identification of novel drugs is therefore urgent. Here, we present a semi-automated and objective method to assess the activity of compounds on one of the key life stages of the parasite: the newly excysted juveniles (NEJ). This stage is highly motile and motility assessment can be exploited to screen for bioactive compounds. Using time-lapse imaging, we quantified NEJ movement after drug exposure. From a panel of ten tested reference anthelmintics, two known fasciolicides (triclabendazole and benzamidoquinazolinone) and three additional compounds (MMV665807, niclosamide, and niclosamide ethanolamine) displayed particularly strong activity and were selected for further investigation. This method represents a robust tool for drug screening and facilitates the discovery of new compounds against F. hepatica.
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BibTeX
@article{bernal2026semiautomated,
title = {{A new semi-automated, motility-based screening assay for discovery of compounds with activity against the juvenile stage of Fasciola hepatica}},
author = {Alice Bernal and Diana S. Gliga and Giulia Colangeli and Matías Preza and Rossitza N. Irobalieva and Caroline F. Frey and Andrew Hemphill and Britta Lundström-Stadelmann and Natalie Wiedemar},
journal = {PLOS Neglected Tropical Diseases},
year = {2026},
month = oct,
doi = {10.1371/journal.pntd.0014491},
url = {https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0014491},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - A new semi-automated, motility-based screening assay for discovery of compounds with activity against the juvenile stage of Fasciola hepatica
AU - Alice Bernal
AU - Diana S. Gliga
AU - Giulia Colangeli
AU - Matías Preza
AU - Rossitza N. Irobalieva
AU - Caroline F. Frey
AU - Andrew Hemphill
AU - Britta Lundström-Stadelmann
AU - Natalie Wiedemar
PY - 2026
DA - 2026/10/26
JO - PLOS Neglected Tropical Diseases
DO - 10.1371/journal.pntd.0014491
UR - https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0014491
AB - Fasciola hepatica is a trematode parasite responsible for fasciolosis, a liver disease that affects humans and livestock worldwide. Together with other food-borne trematode infections, fasciolosis is considered a neglected tropical disease. Further, it imposes substantial agricultural losses due to infections in ruminants. No vaccine is currently available, and control heavily relies on drug treatment, especially with triclabendazole (TCBZ). However, the intensive use of TCBZ over the past four decades has led to increasing rates of treatment failures and the emergence of drug-resistant parasites. Therefore, the identification of new treatment options is an urgent priority. The currently available toolset for drug screening, however, is limited. To address this need, we established a novel, semi-automated, standardized, and objective screening assay based on motility monitoring of newly excysted juveniles using microscopic live imaging. The assay was validated by testing a panel of ten compounds with known anthelmintic properties, amongst them TCBZ (IC50: 1.5 µM) and the new activator of the F. hepatica transient receptor potential melastatin (TRPMPZQ) ion channel, benzamidoquinazolinone (IC50: 1.05 µM). In addition to these two compounds with known activity against F. hepatica, three compounds were identified as particularly promising with a fast onset of action and IC50 values in the nanomolar range: the salicylanilides MMV665807 (IC50: 44 nM), niclosamide (IC50: 32 nM), and its ethanolamine salt, niclosamide ethanolamine (IC50: 9 nM). Complementary live/dead staining revealed that only TCBZ displayed parasiticidal activity, while the other compounds, although leading to parasite paralysis, did not lead to parasite death within 72 hours. Scanning electron microscopy of drug treated parasites did not reveal any significant damage at concentrations corresponding to the IC50s, but strong phenotypes were visible at 20 µM. The presented motility assay provides a robust method for the discovery of novel anthelmintic compounds and facilitates the ongoing effort to combat fasciolosis. Author summary: Fasciola hepatica, the common liver fluke, is a parasitic platyhelminth that infects the liver and biliary ducts of humans and livestock, causing fasciolosis, a Neglected Tropical Disease as defined by the World Health Organization. Triclabendazole is the drug of choice to treat humans and animals. However, its intensive use has led to the emergence of drug resistance resulting in treatment failures worldwide. The identification of novel drugs is therefore urgent. Here, we present a semi-automated and objective method to assess the activity of compounds on one of the key life stages of the parasite: the newly excysted juveniles (NEJ). This stage is highly motile and motility assessment can be exploited to screen for bioactive compounds. Using time-lapse imaging, we quantified NEJ movement after drug exposure. From a panel of ten tested reference anthelmintics, two known fasciolicides (triclabendazole and benzamidoquinazolinone) and three additional compounds (MMV665807, niclosamide, and niclosamide ethanolamine) displayed particularly strong activity and were selected for further investigation. This method represents a robust tool for drug screening and facilitates the discovery of new compounds against F. hepatica.
SN - 1935-2735
SN - 1935-2727
ER -