Book contents
- Frontmatter
- Contents
- List of contributors
- Preface
- General advice
- 1 Observational Exercises on Parasites
- 2 Ecology
- 3 Physiology and Biochemistry
- 4 Pathology and Immunology
- 5 Chemotherapy
- 5.1 Sensitivity of a coccidial parasite, Eimeria, to an ionophore, monensin
- 5.2 Egg hatch assay for determination of resistance of nematodes to benzimidazole anthelmintics
- 5.3 Larval migration inhibition assay for determination of susceptibility of nematodes to levamisole
- 5.4 Effect of anthelmintics on nematodes
- 6 Molecular Parasitology
- 7 Behaviour
- Appendix 1 Reagent index
- Appendix 2 UK suppliers
- Appendix 3 US suppliers
- Index
5.3 - Larval migration inhibition assay for determination of susceptibility of nematodes to levamisole
Published online by Cambridge University Press: 05 June 2012
- Frontmatter
- Contents
- List of contributors
- Preface
- General advice
- 1 Observational Exercises on Parasites
- 2 Ecology
- 3 Physiology and Biochemistry
- 4 Pathology and Immunology
- 5 Chemotherapy
- 5.1 Sensitivity of a coccidial parasite, Eimeria, to an ionophore, monensin
- 5.2 Egg hatch assay for determination of resistance of nematodes to benzimidazole anthelmintics
- 5.3 Larval migration inhibition assay for determination of susceptibility of nematodes to levamisole
- 5.4 Effect of anthelmintics on nematodes
- 6 Molecular Parasitology
- 7 Behaviour
- Appendix 1 Reagent index
- Appendix 2 UK suppliers
- Appendix 3 US suppliers
- Index
Summary
Aims and objectives
This exercise is designed to demonstrate:
The susceptibility of nematode larvae to treatment with levamisole. The assay is based on the paralysing property of the drug and the ability of larvae from resistant strains to migrate at a higher concentration of drug than those of susceptible strains.
Introduction
The widespread use of anthelmintics to control gastrointestinal parasitism in sheep and goats has resulted in the emergence of strains of nematodes resistant to the benzimidazole, levamisole or avermectin group of drug families. In some countries, multiple resistant strains have been selected. In the UK, the majority of cases of anthelmintic resistance are to the drugs in the benzimidazole group, although resistance to avermectins and levamisoles has also been reported. An in vitro test for resistance to avermectins is based on the fact that the paralysis resulting from treatment with this drug inhibits the migratory behaviour of infective third-stage larvae (L3).
The aim is to incubate L3s in serial concentrations of the test drug on a nylon mesh, thus simulating the gut mucosal layer through which the larvae would normally migrate. Paralysis caused by susceptibility to the test drug has the effect of preventing the migration and causing the larvae to be held by the gauze. The percentage of larvae able to migrate at each concentration is determined and a drug response curve plotted (i.e. drug concentration is plotted against percentage migrating through the membrane).
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- Practical Exercises in Parasitology , pp. 321 - 328Publisher: Cambridge University PressPrint publication year: 2001
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