Identification of a novel ß-adrenergic octopamine receptor-like gene (ßAOR-like) and increased ATP-binding cassette B10 (ABCB10) expression in a Rhipicephalus microplus cell line derived from acaricide-resistant ticks

Koh-Tan, H. H., Strachan, E., Cooper, K., Bell-Sakyi, L. and Jonsson, N. N. (2016) Identification of a novel ß-adrenergic octopamine receptor-like gene (ßAOR-like) and increased ATP-binding cassette B10 (ABCB10) expression in a Rhipicephalus microplus cell line derived from acaricide-resistant ticks. Parasites and Vectors, 9, 425. (doi: 10.1186/s13071-016-1708-x) (PMID:27484910) (PMCID:PMC4970269)

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Background: The cattle tick Rhipicephalus (Boophilus) microplus is an economically important parasite of livestock. Effective control of ticks using acaricides is threatened by the emergence of resistance to many existing compounds. Several continuous R. microplus cell lines have been established and provide an under-utilised resource for studies into acaricide targets and potential genetic mutations associated with resistance. As a first step to genetic studies using these resources, this study aimed to determine the presence or absence of two genes and their transcripts that have been linked with acaricide function in cattle ticks: β-adrenergic octopamine receptor (βAOR, associated with amitraz resistance) and ATP-binding cassette B10 (ABCB10, associated with macrocyclic lactone resistance) in six R. microplus cell lines, five other Rhipicephalus spp. cell lines and three cell lines representing other tick genera (Amblyomma variegatum, Ixodes ricinus and Hyalomma anatolicum). Methods: End-point polymerase chain reaction (PCR) was used for detection of the βAOR gene and transcripts in DNA and RNA extracted from the tick cell lines, followed by capillary sequencing of amplicons. Quantitative real-time PCR (qPCR) was performed to determine the levels of expression of ABCB10. Results: βAOR gene expression was detected in all Rhipicephalus spp. cell lines. We observed a second amplicon of approximately 220 bp for the βAOR gene in the R. microplus cell line BME/CTVM6, derived from acaricide-resistant ticks. Sequencing of this transcript variant identified a 36 bp insertion in the βAOR gene, leading to a 12-amino acid insertion (LLKTLALVTIIS) in the first transmembrane domain of the protein. In addition, nine synonymous SNPs were also discovered in R. appendiculatus, R. evertsi and R. sanguineus cell lines. Some of these SNPs appear to be unique to each species, providing potential tools for differentiating the tick species. The BME/CTVM6 cell line had significantly higher ABCB10 (P = 0.002) expression than the other R. micropluscell lines. Conclusions: The present study has identified a new βAOR gene and demonstrated a higher ABCB10 expression level in the BME/CTVM6 cell line, indicating that tick cell lines provide a useful experimental tool for acaricide resistance studies and further elucidation of tick genetics.

Item Type:Articles
Additional Information:This project was funded through ES’s honours project and BBSRC research experience placement (REP) awarded to KC (through allocations of REPs direct to University of Glasgow, School of Veterinary Medicine 2015). LBS is supported by the United Kingdom Biotechnology and Biological Sciences Research Council’s Institute Strategic Programme Grant (BBS/E/I/00001741) to the Pirbright Institute.
Glasgow Author(s) Enlighten ID:Jonsson, Professor Nicholas and Koh-Tan, Dr Caline
Authors: Koh-Tan, H. H., Strachan, E., Cooper, K., Bell-Sakyi, L., and Jonsson, N. N.
College/School:College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine
Journal Name:Parasites and Vectors
Publisher:BioMed Central
ISSN (Online):1756-3305
Copyright Holders:Copyright © 2016 The Authors
First Published:First published in Parasites and Vectors 9:425
Publisher Policy:Reproduced under a creative commons license

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
705311Acaricide targets in ticks of livestock: comparative study using tick cell cultures (BBSRC Research Experience Placement 2015)Nicholas JonssonBiotechnology and Biological Sciences Research Council (BBSRC)UNSPECIFIEDRI BIODIVERSITY ANIMAL HEALTH & COMPMED