Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2017 Apr;7(1):83-89.
doi: 10.1016/j.ijpddr.2017.01.005. Epub 2017 Jan 27.

A novel in vitro image-based assay identifies new drug leads for giardiasis

Affiliations

A novel in vitro image-based assay identifies new drug leads for giardiasis

Christopher J S Hart et al. Int J Parasitol Drugs Drug Resist. 2017 Apr.

Abstract

Giardia duodenalis is an intestinal parasite that causes giardiasis, a widespread human gastrointestinal disease. Treatment of giardiasis relies on a small arsenal of compounds that can suffer from limitations including side-effects, variable treatment efficacy and parasite drug resistance. Thus new anti-Giardia drug leads are required. The search for new compounds with anti-Giardia activity currently depends on assays that can be labour-intensive, expensive and restricted to measuring activity at a single time-point. Here we describe a new in vitro assay to assess anti-Giardia activity. This image-based assay utilizes the Perkin-Elmer Operetta® and permits automated assessment of parasite growth at multiple time points without cell-staining. Using this new approach, we assessed the "Malaria Box" compound set for anti-Giardia activity. Three compounds with sub-μM activity (IC50 0.6-0.9 μM) were identified as potential starting points for giardiasis drug discovery.

Keywords: Drug discovery; Giardia; Image-based assay; Malaria Box.

PubMed Disclaimer

Figures

Image 1
Graphical abstract
Fig. 1
Fig. 1
Automatic enumeration of Giardia tropozoites by digital phase-contrast microscopy paired with Harmony® and Phenologic™ automated counting. Giardia trophozoites seeded in 96-well micro-titre plates were imaged using brightfield (A) and digital phase-contrast microscopy (B). Images were automatically assessed by Harmony® and Phenologic™ to identify and count trophozoites (green) amongst other signals (red) (C; brightfield and D; digital phase-contrast images). The effectiveness of the automated counting strategy was determined by comparing automated counts (E and F; green bars) to manually determining parasite numbers (E and F; grey bars). Parasite cultures were initiated at seeding concentrations of 2 × 104 - 5 × 103 cells/well and cell numbers were determined at 24 (E) and 48 h (F). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
Fig. 2
Fig. 2
Parasite growth assessment. The growth of Giardia trophozoites in assay conditions was assessed by digital phase-contrast microscopy (A). Parasite cultures were established in 96-well micro-titre plates at different seeding concentrations and growth was assesed at 24 (dark grey) and 48 h (light grey). Data are presented as mean parasite count ± SD of three independent experiments, each carried out in triplicate wells. In separate assays, the impact of parasite imaging on growth was assessed by comparing growth in plates imaged at both 24 and 48 h (B; dark grey) to those imaged only at 48 h (B; light grey). Data are presented as mean parasite count ± SD of three independent experiments. There was no significant difference in the growth of parasites grown on plates imaged once at 48 h or at both time points (p = 0.68).
Fig. 3
Fig. 3
Anti-Giardia activity of “Malaria Box” compounds. The antigiardial activity of compounds in the ‘Malaria Box’ was determined using a primary 10 μM screen for 24 (A) and 48 h (B) and a secondary 5 μM screen for 24 (C) and 48 h (D) of compounds active (>50% inhibition) at 10 μM. All data are presented as mean % inhibition with standard error of the mean provided for 5 μM data (C & D).

Similar articles

Cited by

References

    1. Al-Mekhlafi H.M., Al-Maktari M.T., Jani R., Ahmed A., Anuar T.S., Moktar N., Mahdy M.A., Lim Y.A., Mahmud R., Surin J. Burden of Giardia duodenalis infection and its adverse effects on growth of schoolchildren in rural Malaysia. PLoS Negl. Trop. Dis. 2013;7:e2516. - PMC - PubMed
    1. Al-Mekhlafi M.S., Azlin M., Nor Aini U., Shaik A., Sa'iah A., Fatmah M.S., Ismail M.G., Ahmad Firdaus M.S., Aisah M.Y., Rozlida A.R., Norhayati M. Giardiasis as a predictor of childhood malnutrition in Orang Asli children in Malaysia. Trans. R. Soc. Trop. Med. Hyg. 2005;99:686–691. - PubMed
    1. Ansell B.R., McConville M.J., Ma'ayeh S.Y., Dagley M.J., Gasser R.B., Svard S.G., Jex A.R. Drug resistance in Giardia duodenalis. Biotechnol. Adv. 2015;33:888–901. - PubMed
    1. Arguello-Garcia R., Cruz-Soto M., Romero-Montoya L., Ortega-Pierres G. Variability and variation in drug susceptibility among Giardia duodenalis isolates and clones exposed to 5-nitroimidazoles and benzimidazoles in vitro. J. Antimicrob. Chemother. 2004;54:711–721. - PubMed
    1. Bartelt L.A., Roche J., Kolling G., Bolick D., Noronha F., Naylor C., Hoffman P., Warren C., Singer S., Guerrant R. Persistent G. lamblia impairs growth in a murine malnutrition model. J. Clin. Invest. 2013;123:2672–2684. - PMC - PubMed

Publication types

MeSH terms

Substances