title: Potential contribution of P-glycoproteins to macrocyclic lactone resistance in the cattle parasitic nematode Cooperia oncophora.
abstract: Resistance against macrocyclic lactones such as ivermectin is widespread among parasitic gastrointestinal nematodes of small ruminants and is rapidly increasing in cattle parasites. ABC transporters of the subfamily B, the so-called P-glycoproteins (Pgps) have been frequently implicated in ivermectin resistance and are a major cause of multi-drug resistance in protozoa and helminths. The Pgp inhibitor verapamil (VPL) dramatically enhanced susceptibility of the cattle parasitic nematode Cooperia oncophora to ivermectin in vitro as measured in a larval developmental assay and a larval migration inhibition assay using third stage larvae. Moreover, VPL completely restored susceptibility to ivermectin in a resistant isolate resulting in virtually identical dose-response curves of susceptible and resistant isolates in the presence of VPL. Further characterisation of the molecular mechanisms resulting in Pgp-mediated ivermectin resistance is still hampered by the lack of molecular and biochemical information for Pgps of parasitic nematodes. Using PCR with degenerate primers, fragments of four different C. oncophora Pgps could be amplified and the Conpgp-2, previously implicated in macrocyclic lactone resistance in Haemonchus contortus, and Conpgp-3 full-length cDNAs were obtained by RACE PCR. The pgp sequences presented here contribute important data required to systematically screen resistant C. oncophora isolates for up- or down-regulation of Pgps and for the detection of single nucleotide polymorphisms in Pgps to detect selection of specific Pgp alleles by anthelmintics as early as possible.
authors: Institute for Parasitology and Tropical Veterinary Medicine, Freie University Berlin, 14163 Berlin, Germany. janina.demeler@fu-berlin.de
authors: Janina
authors: J
authors: Demeler
authors: Jürgen
authors: J
authors: Krücken
authors: Salha
authors: S
authors: AlGusbi
authors: Sabrina
authors: S
authors: Ramünke
authors: Jessie
authors: J
authors: De Graef
authors: Dominique
authors: D
authors: Kerboeuf
authors: Peter
authors: P
authors: Geldhof
authors: William E
authors: WE
authors: Pomroy
authors: Georg
authors: G
authors: von Samson-Himmelstjerna
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B / Q000378:metabolism*; D000818:Animals; D000871:Anthelmintics / Q000378:metabolism / Q000494:pharmacology*; D018509:DNA, Helminth / Q000235:genetics; D004351:Drug Resistance; D004791:Enzyme Inhibitors / Q000378:metabolism; D007559:Ivermectin / Q000378:metabolism / Q000494:pharmacology; D007783:Lactones / Q000378:metabolism / Q000494:pharmacology*; D007814:Larva / Q000187:drug effects; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D014251:Trichostrongyloidea / Q000187:drug effects* / Q000378:metabolism*; D014700:Verapamil / Q000378:metabolism
chemical_list: D018435:ATP Binding Cassette Transporter, Subfamily B; D000871:Anthelmintics; D018509:DNA, Helminth; D004791:Enzyme Inhibitors; D007783:Lactones; D007559:Ivermectin; D014700:Verapamil