Assessing anthelmintic resistance risk in the post-genomic era: a proof-of-concept study assessing the potential for widespread benzimidazole-resistant gastrointestinal nematodes in North American cattle and bison.

Elizabeth M Redman,Russell W Avramenko,John S Gilleard,Claire Windeyer

doi:10.1017/s0031182020000426

Elizabeth M Redman, Russell W Avramenko + Show 2 more

Open Access

https://doi.org/10.1017/s0031182020000426

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Journal: Parasitology	Publication Date: Mar 6, 2020
Citations: 25	License type: CC BY 4.0

Affiliation: University of Calgary, Département Santé Animale

Abstract

As genomic research continues to improve our understanding of the genetics of anthelmintic drug resistance, the revolution in DNA sequencing technologies will provide increasing opportunities for large-scale surveillance for the emergence of drug resistance. In most countries, parasite control in cattle and bison has mainly depended on pour-on macrocyclic lactone formulations resulting in widespread ivermectin resistance. Consequently, there is an increased interest in using benzimidazole drugs which have been used comparatively little in cattle and bison in recent years. This situation, together with our understanding of benzimidazole resistance genetics, provides a practical opportunity to use deep-amplicon sequencing to assess the risk of drug resistance emergence. In this paper, we use deep-amplicon sequencing to scan for those mutations in the isotype-1 β-tubulin gene previously associated with benzimidazole resistance in many trichostrongylid nematode species. We found that several of these mutations occur at low frequency in many cattle and bison parasite populations in North America, suggesting increased use of benzimidazole drugs in cattle has the potential to result in widespread emergence of resistance in multiple parasite species. This work illustrates a post-genomic approach to large-scale surveillance of early emergence of anthelmintic resistance in the field.

Highlights

The detection of anthelmintic drug resistance in nematode parasites during the early phases of its emergence is problematic in both animals and humans
Isotype-1 β-tubulin reads were identified in these samples, above the 200 reads per species threshold, for C. oncophora, O. ostertagi, C. punctata, H. placei and T. axei
The F200Y (TTC > TAC) single nucleotide polymorphisms (SNPs) was found above the 0.1% species threshold in all five species, primarily in calves from Oklahoma; C. oncophora, O. ostertagi (15 calves, frequency range 0.29–12.03%), C. punctata (16 calves, frequency range 0.18–7.75%), H. placei (15 calves, frequency range 0.57–27.45%) and T. axei (Fig. 1 and Table 1)

Summary

Introduction

The detection of anthelmintic drug resistance in nematode parasites during the early phases of its emergence is problematic in both animals and humans. By the time resistance is detected, effective mitigation strategies, such as the use of drug combinations and/or refugia management, are already severely comprised. Molecular diagnostic techniques that detect the causal mutations of resistance, or genetically linked markers, have the potential to allow resistance to be detected at an early stage and enable more effective evidence-based resistance management. The identification of known drug resistance mutations at a low frequency in parasite populations that are phenotypically susceptible to anthelmintics may help assess the risk of resistance emergence under the influence of drug selection pressure. We apply deep-amplicon sequencing, using the Illumina MiSeq short read sequencing platform, to detect low-frequency benzimidazole resistanceassociated mutations in cattle and bison parasites as a proof-of-concept and example of a post-genomic approach to resistance surveillance

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Conclusion