Caenorhabditis elegans is a useful model for anthelmintic discovery

Parasitic nematodes infect one quarter of the world's population and impact all humans through widespread infection of crops and livestock. Resistance to current anthelmintics has prompted the search for new drugs. Traditional screens that rely on parasitic worms are costly and labour intensive and target-based approaches have failed to yield novel anthelmintics. Here, we present our screen of 67,012 compounds to identify those that kill the non-parasitic nematode Caenorhabditis elegans. We then rescreen our hits in two parasitic nematode species and two vertebrate models (HEK293 cells and zebrafish), and identify 30 structurally distinct anthelmintic lead molecules. Genetic screens of 19 million C. elegans mutants reveal those nematicides for which the generation of resistance is and is not likely. We identify the target of one lead with nematode specificity and nanomolar potency as complex II of the electron transport chain. This work establishes C. elegans as an effective and cost-efficient model system for anthelmintic discovery

Determining the plasticity of CD34 expression

<p>Determining if OCI-AML-20 cells can regain CD34 expression.</p

Optimizing methodology for the detection of H3K27me3 levels using flow cytometry

<p>Optimizing methods to detect H3K27m3 levels using flow cytometry in patient AML cells.</p

The novel nematicide wact-86 interacts with aldicarb to kill nematodes

<div><p>Parasitic nematodes negatively impact human and animal health worldwide. The market withdrawal of nematicidal agents due to unfavourable toxicities has limited the available treatment options. In principle, co-administering nematicides at lower doses along with molecules that potentiate their activity could mitigate adverse toxicities without compromising efficacy. Here, we screened for new small molecules that interact with aldicarb, which is a highly effective treatment for plant-parasitic nematodes whose toxicity hampers its utility. From our collection of 638 worm-bioactive compounds, we identified 20 molecules that interact positively with aldicarb to either kill or arrest the growth of the model nematode <i>Caenorhabditis elegans</i>. We investigated the mechanism of interaction between aldicarb and one of these novel nematicides called wact-86. We found that the carboxylesterase enzyme GES-1 hydrolyzes wact-86, and that the interaction is manifested by aldicarb’s inhibition of wact-86’s metabolism by GES-1. This work demonstrates the utility of <i>C</i>. <i>elegans</i> as a platform to search for new molecules that can positively interact with industrial nematicides, and provides proof-of-concept for prospective discovery efforts.</p></div

Aldicarb potentiates wact-86 activity by inhibiting its GES-1-dependent hydrolysis.

<p><b>(A)</b> wact-86 dose-response assays, plus and minus 20 μM aldicarb, for wild-type worms and two strains harbouring <i>ges-1</i> deletion alleles. <b>(B)</b> Quantification of wact-86 metabolite accumulation in wild-type worms incubated in wact-86 alone or in combination with aldicarb. <b>(C)</b> Quantification of wact-86 accumulation in wild-type worms incubated in wact-86 alone or in combination with aldicarb. For B and C, the area under the curve (AUC) values for the wact-86 parent and metabolite were calculated as in <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0005502#pntd.0005502.g003" target="_blank">Fig 3</a>. One and three asterisks indicate student’s t-test p < 0.05 and p < 0.001, respectively, compared to the aldicarb-untreated condition. Error bars represent the s.e.m.</p

The novel nematicide wact-86 interacts with aldicarb to kill <i>C</i>. <i>elegans</i>.

<p><b>(A)</b> The chemical structure of wact-86. <b>(B)</b> Combination dose-response matrix for wact-86 and aldicarb. Worm abundance, relative to the DMSO control, is represented by a colour-coded scale ranging from 0 (no viable worms) to ≥1 (at least as many viable worms as DMSO control). See <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0005502#sec009" target="_blank">Methods</a> for how the relative worm abundance value was calculated.</p

Wact-86 resistant mutants harbour missense mutations in the carboxylesterase gene <i>ges-1</i>.

<p><b>(A)</b> wact-86 dose-response assays for wild-type worms and the three wact-86 resistant mutants. For each resistant strain the <i>ges-1</i> allele and the GES-1 amino acid substitution are indicated (see <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0005502#pntd.0005502.s010" target="_blank">S2 File</a> for the whole genome sequencing data obtained for the resistant mutants). <b>(B)</b> Sequence alignment of the <i>C</i>. <i>elegans</i> GES-1 protein with the orthologous carboxylesterases from fly, fish, mouse, and human. For clarity, only the segment that is mutated in the wact-86 resistant strains is shown. Conserved residues are highlighted in black. The two GES-1 residues that are mutated in the wact-86 resistant strains are highlighted in grey. The asterisk denotes the conserved histidine that is part of the enzyme’s catalytic triad.</p

The HPLC solvent and flow rate gradients used herein.

<p>Solvent A is 4.9:95:0.1 (ACN:H₂O:Acetic Acid); Solvent B is 95:4.9:0.1 (ACN: H₂O:Acetic Acid).</p

Author Correction: Caenorhabditis elegans is a useful model for anthelmintic discovery

An amendment to this paper has been published and can be accessed via a link at the top of the paper