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      Diethylcarbamazine mediated potentiation of emodepside induced paralysis requires TRP-2 in adult Brugia malayi


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          Human and veterinary filarial nematode infections are a major health concern in tropical countries. They are transmitted by biting insects and mosquitoes. Lymphatic filariasis, a group of filarial infections caused by Brugia spp. and Wucheria bancrofti affect more than 120 million people worldwide. Infected individuals develop swollen limbs and disfigurement, leading to an inability to work and ostracization from society. Control and prophylaxis for these infections involve mass drug administration combinations of anthelmintics including diethylcarbamazine (DEC). DEC has actions on microfilariae, but its effects on adult worms are less pronounced. The SLO-1 (BK) channel activator, emodepside, kills adults of many filarial species. However, the in vivo efficacy of emodepside is suboptimal against B. malayi, possibly due to reduced bioavailability in the lymphatic system. Expressing different slo-1 splice variants in B. malayi also affects sensitivity to emodepside. This study explores the potentiation of emodepside mediated paralysis by DEC in adult female B. malayi. Worminator motility measurements show that co-application of DEC and emodepside increases the potency of emodepside 4-fold. The potentiation of the emodepside effect persists even after the worms recover (desensitize) from the initial effects of DEC. RNAi knock-down demonstrates that the DEC-mediated potentiation of emodepside requires the presence of TRP-2 channels. Our study demonstrates that the addition of DEC could enhance the effect of emodepside where bioavailability or activity against a specific species may be low.

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          A new mathematical model for relative quantification in real-time RT-PCR.

          M. Pfaffl (2001)
          Use of the real-time polymerase chain reaction (PCR) to amplify cDNA products reverse transcribed from mRNA is on the way to becoming a routine tool in molecular biology to study low abundance gene expression. Real-time PCR is easy to perform, provides the necessary accuracy and produces reliable as well as rapid quantification results. But accurate quantification of nucleic acids requires a reproducible methodology and an adequate mathematical model for data analysis. This study enters into the particular topics of the relative quantification in real-time RT-PCR of a target gene transcript in comparison to a reference gene transcript. Therefore, a new mathematical model is presented. The relative expression ratio is calculated only from the real-time PCR efficiencies and the crossing point deviation of an unknown sample versus a control. This model needs no calibration curve. Control levels were included in the model to standardise each reaction run with respect to RNA integrity, sample loading and inter-PCR variations. High accuracy and reproducibility (<2.5% variation) were reached in LightCycler PCR using the established mathematical model.
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            Mode of action of benzimidazoles.

            Benzimidazoles represent the only class of truly broad-spectrum anthelmintics, however, they also show activity against fungi and mammalian cells. This raises the question as to why benzimidazoles can selectively kill helminths and yet exhibit little or no mammalian toxicity. In this paper, Ernest Lacey examines this example of selectivity of drug action to the ubiquitous target of these drugs, the structural protein, tubulin.
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              Glutamate-gated chloride channels and the mode of action of the avermectin/milbemycin anthelmintics.

              The macrocyclic lactones are the biggest selling and arguably most effective anthelmintics currently available. They are good substrates for the P-glycoproteins, which might explain their selective toxicity for parasites over their vertebrate hosts. Changes in the expression of these pumps have been implicated in resistance to the macrocyclic lactones, but it is clear that they exert their anthelmintic effects by binding to glutamate-gated chloride channels expressed on nematode neurones and pharyngeal muscle cells. This effect is quite distinct from the channel opening induced by glutamate, the endogenous transmitter acting at these receptors, which produces rapidly opening and desensitising channels. Ivermectin-activated channels open very slowly but essentially irreversibly, leading to a very long-lasting hyperpolarisation or depolarisation of the neurone or muscle cell and therefore blocking further function. Molecular and genetic studies have shown that there are multiple GluCl isoforms in both free-living and parasitic nematodes: the exact genetic make-up and functions of the GluCl may vary between species. The known expression patterns of the GluCl explain most of the observed biological effects of treatment with the macrocyclic lactones, though the reason for the long-lasting inhibition of larval production in filarial species is still poorly understood.

                Author and article information

                Int J Parasitol Drugs Drug Resist
                Int J Parasitol Drugs Drug Resist
                International Journal for Parasitology: Drugs and Drug Resistance
                29 October 2022
                December 2022
                29 October 2022
                : 20
                : 108-112
                [1]Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, 50011, USA
                Author notes
                []Corresponding author. rjmartin@ 123456iastate.edu
                © 2022 Published by Elsevier Ltd on behalf of Australian Society for Parasitology.

                This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

                : 15 July 2022
                : 14 October 2022
                : 17 October 2022
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