Parasitology



Genetic variability of glutamate-gated chloride channel genes in ivermectin-susceptible and -resistant strains of Cooperia oncophora


A. I. NJUE a1 and R. K. PRICHARD a1c1
a1 Institute of Parasitology, McGill University, 21 111 Lakeshore Road, Ste-Anne-de-Bellevue, Quebec, Canada, H9X 3V9

Article author query
njue ai   [PubMed][Google Scholar] 
prichard rk   [PubMed][Google Scholar] 

Abstract

The glutamate-gated chloride channels (GluCls) are members of the ligand-gated ion channel superfamily that are thought to be involved in the mode of action of ivermectin and mechanism of resistance. Using reverse-transcriptase PCR techniques, 2 full-length GluCl cDNAs, encoding GluClα3 and GluClβ subunits, were cloned from Cooperia oncophora, a nematode parasite of cattle. The two sequences show a high degree of identity to similar subunits from other nematodes. The C. oncophora GluClα3 subunit is most closely related to the Haemonchus contortus GluClα3B subunit, while C. oncophora GluClβ subunit shares high sequence identity with the H. contortus GluClβ subunit. Using single-strand conformation polymorphism, the genetic variability of these two genes was analysed in an ivermectin-susceptible isolate and an ivermectin-resistant field isolate of C. oncophora. Statistical analysis suggested an association between the C. oncophora GluClα3 gene and ivermectin resistance. No such association was seen with the GluClβ gene.

(Received April 7 2004)
(Revised May 13 2004)
(Revised May 21 2004)
(Accepted May 21 2004)


Key Words: Cooperia oncophora; genetic variation; ivermectin resistance; glutamate-gated chloride channel; single-strand conformation polymorphism.

Correspondence:
c1 Institute of Parasitology, McGill University, 21 111 Lakeshore Road, Ste-Anne-de-Bellevue, Quebec, Canada, H9X 3V9. Tel: +514 398 7792. Fax: +514 398 7857. E-mail: roger.prichard@mcgill.ca


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