Development and validation of an in vitro Trichostrongylus colubriformis motility assay

Folz, S.D.; Pax, Ralph A.; Bennett, James L.; Lee, B.L.; Conder, George A.

doi:10.1016/0020-7519(87)90080-4

Cited by 21 publications

(3 citation statements)

References 14 publications

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“…Such tests are potential options for detecting anthelmintic resis- tance because they are cheap, relatively quick to perform, preclude host influences and, as they can be run over a concentration range, may provide reproducible parameters with which to measure phenotype (Demeler et al, 2013). Several studies utilising ruminant parasitic nematodes have indicated that motility and migration tests are useful tools for informing on the ML sensitivity of single species populations (Martin and Le Jambre, 1979;Folz et al, 1987;Sangster et al, 1988;Demeler et al, 2010Demeler et al, , 2012Demeler et al, , 2013. Here, we examined the value of the LMIT for use with cyathostomin larvae obtained by culture from equine faeces.…”

Section: Discussionmentioning

confidence: 99%

Development of the larval migration inhibition test for comparative analysis of ivermectin sensitivity in cyathostomin populations

McArthur

Handel

Robinson

et al. 2015

Veterinary Parasitology

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Cyathostomins are the most prevalent parasitic pathogens of equids worldwide. These nematodes have been controlled using broad-spectrum anthelmintics; however, cyathostomin resistance to each anthelmintic class has been reported and populations insensitive to more than one class are relatively commonplace. The faecal egg count reduction test (FECRT) is considered the most suitable method for screening anthelmintic sensitivity in horses, but is subject to variation and is relatively time-consuming to perform. Here, we describe a larval migration inhibition test (LMIT) to assess ivermectin (IVM) sensitivity in cyathostomin populations. This test measures the paralysing effect of IVM on the ability of third stage larvae (L3) to migrate through a pore mesh. When L3 from a single faecal sample were examined on multiple occasions, variation in migration was observed: this was associated with the length of time that the L3 had been stored before testing but the association was not significant. Half maximal effective concentration (EC50) values were then obtained for cyathostomin L3 from six populations of horses or donkeys that showed varying sensitivity to IVM in previous FECRTs. Larvae from populations indicated as IVM resistant by FECRT displayed significantly higher EC50 values in the LMIT than L3 from populations classified as IVM sensitive or L3 from populations that had not been previously exposed to IVM or had limited prior exposure. The analysis also showed that EC50 values obtained using L3 from animals in which IVM faecal egg count reduction (FECR) levels had been recorded as <95% were significantly higher than EC50 values obtained using L3 from animals for which FECR was measured as >95%. For one of the populations, time that had elapsed since IVM administration had an effect on the EC50 value obtained, with a longer time since treatment associated with lower EC50 values. These results indicate that the LMIT has value in discriminating IVM sensitivity amongst cyathostomin populations, but several factors were identified that need to be taken into account when executing the test and interpreting the derived data.

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Section: Discussionmentioning

confidence: 99%

Development of the larval migration inhibition test for comparative analysis of ivermectin sensitivity in cyathostomin populations

McArthur

Handel

Robinson

et al. 2015

Veterinary Parasitology

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“…To render the interpretation more objective, a micromotility meter has been developed (11). Folz et al (55,56) used this apparatus to detect drug resistance in H. contortus and T. colubriformis, but other authors have found it less reliable (142; S. Geerts, unpublished results).…”

Section: Detection Of Drug Resistancementioning

confidence: 99%

Drug Resistance in Human Helminths: Current Situation and Lessons from Livestock

Geerts

Gryseels

2000

Clinical Microbiology Reviews

231

130

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“…Another instrument, the Micromotility Meter ™ (B & P Instruments, Mason, MI, USA) was reported to be sensitive and accurate in monitoring and recording the in vitro motility of helminths (Bennet and Pax, 1987). Folz and colleagues developed a motility assay involving this instrument to measure the effects of several anthelmintics (including IVM) in H. contortus and Trichostrongylus colubriformis larvae (Folz et al 1987 a , b ). The principle of this device is the measurement of reflected light rays.…”

Section: Introductionmentioning

confidence: 99%

Measuring the effect of avermectins and milbemycins on somatic muscle contraction of adult Haemonchus contortus and on motility of Ostertagia circumcincta in vitro

2014

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The mechanism of anthelmintic resistance against the widely used macrocyclic lactones (MLs) is still not fully understood. Pharyngeal, somatic body muscles and the ovijector have been proposed as putative sites of action as well as resistance. In the present study the effects of three avermectins and three milbemycins on adult parasitic nematodes were evaluated in vitro. The Muscle Transducer system was used to investigate the effects of MLs on muscle contraction in female Haemonchus contortus and effects on motility were measured in Ostertagia (Teladorsagia) circumcincta using the Micromotility Meter. Concentration-response curves for all substances in both systems shifted to the right in the resistant isolates. Resistance was present to ivermectin (IVM) and its components IVM B1a and IVM B1b, suggesting that both components are involved in the mode of action and resistance. No consistent patterns of potency and resistance of the substances were observed except that milbemycins generally showed lower resistance ratios (RRs) than IVM. IVM and IVM B1b were the most potent inhibitors of contraction and motility in both susceptible isolates and also showed the highest RR in both species. Low RRs for milbemycins recorded in vitro for highly resistant isolates in vivo suggest that other factors such as pharmacokinetics influence drug potency in vivo.

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Development and validation of an in vitro Trichostrongylus colubriformis motility assay

Cited by 21 publications

References 14 publications

Development of the larval migration inhibition test for comparative analysis of ivermectin sensitivity in cyathostomin populations

Development of the larval migration inhibition test for comparative analysis of ivermectin sensitivity in cyathostomin populations

Drug Resistance in Human Helminths: Current Situation and Lessons from Livestock

Measuring the effect of avermectins and milbemycins on somatic muscle contraction of adult Haemonchus contortus and on motility of Ostertagia circumcincta in vitro

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