Novel assay for the detection and monitoring of levamisole resistance in Haemonchus contortus
2014
Barrère, Virginie | Beech, Robin | Charvet, Claude | Prichard, Roger K. | Institute of Parasitology ; McGill University = Université McGill [Montréal, Canada] | Infectiologie et Santé Publique (UMR ISP) ; Institut National de la Recherche Agronomique (INRA)-Université de Tours (UT) | le Ministere du Developpement economique, Innovation et Exportation Quebec; Natural Sciences and Engineering Research Council, Canada
International audience
Show more [+] Less [-]English. A levamisole-sensitive acetylcholine receptor has recently been described in the parasitic nematode Hoemonchus contortus. The pentameric receptor is produced from different subunit proteins, one of which is Hco-ACR-8. A truncated transcript, Hco-acr-8b, has been identified in six levamisole-resistant H. contortus isolates and was found to be absent in four levamisole-susceptible isolates, indicating Hco-acr-8b could be a potential marker for levamisole resistance. The Hco-acr-8b transcript contains exons 1 and 2 and terminates with 347 bp from within the intron 2. In this work, we investigated genomic DNA sequences of the Hco-acr-8 gene, in a region including exon 2 and exon 3, from a wide range of levamisole-susceptible and resistant H. contortus isolates. Sequences potentially involved in generating the truncated splice variant within the second intron were analysed from individuals and pools of parasites. We found an insertion/deletion (indel) of 63 bp located just downstream from the splice acceptor site for the alternative third exon. The sequence of the indel, when present, was similar in the 12 isolates examined. The presence or absence of this indel was statistically (Chi(2) test) correlated with levamisole resistance status. A correlation was also demonstrated between the absence of the indel and the expression of the Hco-acr-8b transcript. We believe this is the first report of a putative DNA marker for levamisole resistance detection. Using this new knowledge, we have developed a novel DNA-based assay for the detection and monitoring of levamisole resistance in parasitic nematodes of animals.
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