title: Novel assay for the detection and monitoring of levamisole resistance in Haemonchus contortus.
abstract: A levamisole-sensitive acetylcholine receptor has recently been described in the parasitic nematode Haemonchus 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 347bp 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 63bp 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.
authors: Institute of Parasitology, McGill University, Macdonald Campus, 21,111 Lakeshore Road, St Anne-de-Bellevue, QC H9X3V9, Canada.
authors: Virginie
authors: V
authors: Barrère
authors: Institute of Parasitology, McGill University, Macdonald Campus, 21,111 Lakeshore Road, St Anne-de-Bellevue, QC H9X3V9, Canada; INRA, UMR1282 Infectiologie et Santé Publique, F-37380 Nouzilly, France.
authors: Robin N
authors: RN
authors: Beech
authors: INRA, UMR1282 Infectiologie et Santé Publique, F-37380 Nouzilly, France; Université François Rabelais de Tours, UMR1282 Infectiologie et Santé Publique, F-37000 Tours, France.
authors: Claude L
authors: CL
authors: Charvet
authors: Institute of Parasitology, McGill University, Macdonald Campus, 21,111 Lakeshore Road, St Anne-de-Bellevue, QC H9X3V9, Canada. Electronic address: roger.prichard@mcgill.ca.
authors: Roger K
authors: RK
authors: Prichard
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000969:Antinematodal Agents / Q000494:pharmacology*; D001483:Base Sequence; D018509:DNA, Helminth / Q000235:genetics; D004351:Drug Resistance / Q000235:genetics*; D017238:Genes, Helminth; D005819:Genetic Markers; D006189:Haemonchus / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D015801:Helminth Proteins / Q000235:genetics; D054643:INDEL Mutation; D007978:Levamisole / Q000494:pharmacology*; D008297:Male; D008969:Molecular Sequence Data; D022821:RNA Splice Sites; D011950:Receptors, Cholinergic / Q000235:genetics
chemical_list: D000969:Antinematodal Agents; D018509:DNA, Helminth; D005819:Genetic Markers; D015801:Helminth Proteins; D022821:RNA Splice Sites; D011950:Receptors, Cholinergic; D007978:Levamisole
keywords: Genetic marker; Haemonchus contortus; Hco-acr-8; Hco-acr-8b; Levamisole resistance