title: Haemonchus contortus P-glycoprotein-2: in situ localisation and characterisation of macrocyclic lactone transport.
abstract: Haemonchus contortus is a veterinary nematode that infects small ruminants, causing serious decreases in animal production worldwide. Effective control through anthelmintic treatment has been compromised by the development of resistance to these drugs, including the macrocyclic lactones. The mechanisms of resistance in H. contortus have yet to be established but may involve efflux of the macrocyclic lactones by nematode ATP-binding-cassette transporters such as P-glycoproteins. Here we report the expression and functional activity of H. contortus P-glycoprotein 2 expressed in mammalian cells and characterise its interaction with the macrocyclic lactones, ivermectin, abamectin and moxidectin. The ability of H. contortus P-glycoprotein 2 to transport different fluorophore substrates was markedly inhibited by ivermectin and abamectin in a dose-dependent and saturable way. The profile of transport inhibition by moxidectin was markedly different. H. contortus P-glycoprotein 2 was expressed in the pharynx, the first portion of the worm's intestine and perhaps in adjacent nervous tissue, suggesting a role for this gene in regulating the uptake of avermectins and in protecting nematode tissues from the effects of macrocyclic lactone anthelmintic drugs. H. contortus P-glycoprotein 2 may thus contribute to resistance to these drugs in H. contortus.
authors.affiliation: Institute of Parasitology, Macdonald Campus, McGill University, 21,111 Lakeshore Road, Ste-Anne-de-Bellevue, H9X3V9 QC, Canada.
authors.forename: Pablo
authors.initials: P
authors.lastname: Godoy
authors.affiliation: Institute of Parasitology, Macdonald Campus, McGill University, 21,111 Lakeshore Road, Ste-Anne-de-Bellevue, H9X3V9 QC, Canada.
authors.forename: Jing
authors.initials: J
authors.lastname: Lian
authors.affiliation: Institute of Parasitology, Macdonald Campus, McGill University, 21,111 Lakeshore Road, Ste-Anne-de-Bellevue, H9X3V9 QC, Canada. Electronic address: roger.prichard@mcgill.ca.
authors.forename: Robin N
authors.initials: RN
authors.lastname: Beech
authors.affiliation: Institute of Parasitology, Macdonald Campus, McGill University, 21,111 Lakeshore Road, Ste-Anne-de-Bellevue, H9X3V9 QC, Canada.
authors.forename: Roger K
authors.initials: RK
authors.lastname: Prichard
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B / Q000032:analysis*; D000825:Animal Structures / Q000737:chemistry; D000818:Animals; D000871:Anthelmintics / Q000378:metabolism*; D001693:Biological Transport, Active; D004351:Drug Resistance; D020869:Gene Expression Profiling; D006189:Haemonchus / Q000737:chemistry* / Q000187:drug effects / Q000378:metabolism*; D007559:Ivermectin / Q000031:analogs & derivatives / Q000378:metabolism; D007783:Lactones / Q000378:metabolism*; D047028:Macrocyclic Compounds / Q000378:metabolism*; D018942:Macrolides / Q000378:metabolism; D000097202:ATP-Binding Cassette Sub-Family B Member 4
chemical_list: D018435:ATP Binding Cassette Transporter, Subfamily B; D000871:Anthelmintics; D007559:Ivermectin; D007783:Lactones; D047028:Macrocyclic Compounds; D018942:Macrolides; D000097202:ATP-Binding Cassette Sub-Family B Member 4; C048324:abamectin; C027837:moxidectin
keywords: Anthelmintic resistance; Heterologous expression system; Ivermectin; Macrocyclic lactones; Moxidectin; Nematode P-glycoprotein; Protein localisation; Transport studies