title: Evaluation of the in vitro expression of ATP binding-cassette (ABC) proteins in an Ixodes ricinus cell line exposed to ivermectin.
abstract: BACKGROUND
  Ticks are among the most important vectors of pathogens causing human and animal disease. Acaricides are used to control tick infestation, although there are increasing reports of resistance. Recently, over-expression of ATP-binding cassette (ABC) transporter proteins (P-glycoproteins, PgP) has been implicated in resistance to the acaricide ivermectin in the ticks Rhipicephalus (Boophilus) microplus and Rhipicephalus sanguineus sensu lato. Ixodid tick cell lines have been used to investigate drug resistance mechanisms. The aim of the present study was to evaluate expression of several PgPs in the Ixodes ricinus-derived cell line IRE/CTVM19 and to determine modulation of expression following treatment with ivermectin.
  
  
  RESULTS
  IRE/CTVM19 cells were treated with different concentrations of ivermectin (0, 11, 22 or 33 μM) and incubated for 10 days. Evaluation of viability and relative expression of ABCB1, ABCB6, ABCB8 and ABCB10 genes were carried out at day 10 post treatment. Cell viability ranged between 84% and 92% with no significant differences between untreated and treated cells. qRT-PCR showed that ABC pump expression was not significantly modulated by ivermectin treatment. Expression of the ABCB8 PgP subfamily revealed a biphasic trend, based on the ivermectin concentration. ABCB6 and ABCB10 gene expression was not modulated by ivermectin treatment and ABCB1 expression was not detected.
  
  
  CONCLUSIONS
  This is the first report of PgP expression in an I. ricinus-derived tick cell line. Development of an in vitro model for the study of acaricide resistance mechanisms would greatly facilitate screening for drug resistance in ticks.
authors.affiliation: Department of Veterinary Sciences, University of Parma, 43126, Parma, Italy.
authors.forename: Carlo
authors.initials: C
authors.lastname: Mangia
authors.affiliation: Department of Veterinary Sciences, University of Parma, 43126, Parma, Italy.
authors.forename: Alice
authors.initials: A
authors.lastname: Vismarra
authors.affiliation: Department of Veterinary Sciences, University of Parma, 43126, Parma, Italy. kramerlh@unipr.it.
authors.forename: Laura
authors.initials: L
authors.lastname: Kramer
authors.affiliation: The Pirbright Institute, Ash Road, Pirbright, Surrey GU24 0NF, Pirbright, UK.
authors.forename: Lesley
authors.initials: L
authors.lastname: Bell-Sakyi
authors.affiliation: Department of Environmental Biology, University of Rome 'La Sapienza', Rome, Italy.
authors.forename: Daniele
authors.initials: D
authors.lastname: Porretta
authors.affiliation: Department of Veterinary Medicine, University of Bari, 70010, Bari, Italy.
authors.forename: Domenico
authors.initials: D
authors.lastname: Otranto
authors.affiliation: Department of Veterinary Science and Public Health, University of Milan, Milan, Italy.
authors.forename: Sara
authors.initials: S
authors.lastname: Epis
authors.affiliation: National Veterinary Institute, SVA, SE-751 89, Uppsala, Sweden.
authors.forename: Giulio
authors.initials: G
authors.lastname: Grandi
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics* / Q000378:metabolism; D056810:Acaricides / Q000494:pharmacology; D000818:Animals; D060829:Arthropod Proteins / Q000235:genetics* / Q000378:metabolism; D002460:Cell Line; D004351:Drug Resistance; D007559:Ivermectin / Q000494:pharmacology*; D018884:Ixodes / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D056810:Acaricides; D060829:Arthropod Proteins; D007559:Ivermectin
keywords: ATP-binding cassette transporter; Ivermectin; Ixodes ricinus; Tick cell line; in vitro