title: Two benzimidazole resistance-associated SNPs in the isotype-1 β-tubulin gene predominate in Haemonchus contortus populations from eight regions in China.
abstract: Haemonchus contortus is one of the most important parasitic nematodes of small ruminants around the world, particularly in tropical and subtropical regions. The control of haemonchosis relies mainly on anthelmintics, but the excessive and prolonged use of anthelmintics is causing serious drug resistance issues in many countries. As benzimidazole (BZ) anthelmintics have been broadly used in China, we hypothesized that resistance is widespread. Given the link between three known single nucleotide polymorphisms (SNPs, designated F167Y, E198A and F200Y) in the isotype-1 β-tubulin gene and BZ resistance, our goal here was to explore the presence of these mutations in H. contortus from small ruminants (sheep and goats) from eight provinces in China using PCR-coupled sequencing. In addition, the genetic diversity and genetic relationship of isotype-1 β-tubulin sequence haplotypes were also investigated. Among 192 H. contortus adult individuals representing the eight populations, we identified six distinct sequence types, five of which had SNP E198A (GCA) and/or F200Y (TAC). Sequence analysis showed that the frequencies of SNPs E198A and F200Y were 0-70% and 0-31%, respectively. SNP F167Y (TAC) was not detected in any population. In addition, high haplotype diversities (0.455-0.939) and nucleotide diversities (0.018-0.039) were calculated. A network analysis of the isotype-1 β-tubulin gene sequences showed that SNPs E198A and F200Y occurred in multiple distinct groupings, suggesting multiple independent origins of these SNPs. The findings of this first study of SNPs in the isotype-1 β-tubulin gene of H. contortus populations suggest that BZ resistance is prevalent in some regions of China, and that any control strategy might focus on monitoring BZ resistance in this country.
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China.
authors.forename: Zongze
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China; Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria 3010, Australia.
authors.forename: Robin B
authors.initials: RB
authors.lastname: Gasser
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China.
authors.forename: Fangyuan
authors.initials: F
authors.lastname: Yin
authors.affiliation: College of Veterinary Medicine, Northwest A&F University, Yangling 712100, China.
authors.forename: Guanghui
authors.initials: G
authors.lastname: Zhao
authors.affiliation: College of Animal Sciences and Veterinary Medicine, Liaoning Medical College, Jingzhou 121000, China.
authors.forename: Min
authors.initials: M
authors.lastname: Bao
authors.affiliation: College of Veterinary Medicine, China Agricultural University, Beijing 100193, China.
authors.forename: Baoliang
authors.initials: B
authors.lastname: Pan
authors.affiliation: Department of Veterinary Medicine, College of Animal Science and Technology, Guangxi University, Nanning 530004, China.
authors.forename: Weiyi
authors.initials: W
authors.lastname: Huang
authors.affiliation: College of Animal Science and Veterinary Medicine, Heilongjiang Bayi Agricultural University, Daqing 163319, China.
authors.forename: Chunren
authors.initials: C
authors.lastname: Wang
authors.affiliation: College of Animal Science and Technology, Yunnan Agricultural University, Kunming 650201, China.
authors.forename: Fengcai
authors.initials: F
authors.lastname: Zou
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China.
authors.forename: Yanqin
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China.
authors.forename: Junlong
authors.initials: J
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Fang
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China. Electronic address: mhu@mail.hzau.edu.cn.
authors.forename: Min
authors.initials: M
authors.lastname: Hu
mesh_terms: D000818:Animals; D000871:Anthelmintics / Q000494:pharmacology*; D001562:Benzimidazoles / Q000494:pharmacology*; D002681:China; D004351:Drug Resistance; D005838:Genotype; D006041:Goats; D006188:Haemonchiasis / Q000453:epidemiology / Q000469:parasitology / Q000662:veterinary; D006189:Haemonchus / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D016133:Polymerase Chain Reaction; D020641:Polymorphism, Single Nucleotide; D015995:Prevalence; D017422:Sequence Analysis, DNA; D012756:Sheep; D014404:Tubulin / Q000235:genetics*
chemical_list: D000871:Anthelmintics; D001562:Benzimidazoles; D014404:Tubulin; C031000:benzimidazole
keywords: Benzimidazole resistance; Haemonchus contortus; Isotype-1 β-tubulin gene; Single nucleotide polymorphism (SNP)