Sustainable parasite control in livestock depends on anthelmintic drugs. The nematode Haemonchus contortus, the most important intestinal parasite of sheep and goats has developed resistance to all classes of anthelmintics including moxidectin, the most potent of the macrocyclic lactones. Pyrosequencing was used to screen H. contortus laboratory and field strains for single nucleotide polymorphisms (SNPs) associated with resistance in three genes, and determine their involvement in field resistance to macrocyclic lactones. Specific SNPs increased in frequency in ivermectin/moxidectin laboratory selected strains for all three genes. These did not protect a resistant field strain from a field dose of ivermectin and were not the major mechanism of resistance in the field strain. A gamma-aminobutyric acid chloride receptor SNP may be a potential marker for moxidectin resistance in the field. This study indicates results obtained from laboratory strains selected with sub-therapeutic doses of drug may not reflect the situation in the field.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.82236 |
| Date | January 2004 |
| Creators | Galazzo, Daniel |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Science (Institute of Parasitology.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 002227499, proquestno: AAIMR12447, Theses scanned by UMI/ProQuest. |
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