ITS2 rDNA and isotype-1 beta-tubulin nemabiome metabarcoding to investigate gastrointestinal nematode diversity and benzimidazole resistance in sympatric sheep, cattle and feral goats

Parasitic gastrointestinal nematodes threaten the productivity of grazing livestock and anthelmintic resistance has emerged globally. Many wild ruminant species live in sympatry with livestock and are susceptible to generalist nematodes that could be carrying either the susceptible or anthelmintic-resistant genotype. A better understanding of the occurrence of the resistant genotype in wild ruminants who have never been treated with anthelmintics is required for sustainable livestock management. We applied ITS2 rDNA and isotype-1 beta-tubulin deep amplicon sequencing to larval samples obtained from the faeces of feral goats and sympatric sheep and cattle. Our results show the power of this approach, providing the first molecular evidence of feral goats as reservoirs of benzimidazole-resistant generalist nematodes, and revealing a cryptic species of Teladorsagia circumcincta.

寄生性胃肠道线虫（Parasitic gastrointestinal nematodes）威胁放牧家畜的生产性能，且驱虫药耐药性（anthelmintic resistance）已在全球范围内出现。诸多野生反刍动物（wild ruminant species）与家畜同域分布，且易感染泛宿主性线虫（generalist nematodes）——这类线虫可携带易感基因型（susceptible genotype）或驱虫药耐药基因型（anthelmintic-resistant genotype）。针对从未接受过驱虫药治疗的野生反刍动物，深入解析其体内耐药基因型的存在情况，是实现可持续家畜管理（sustainable livestock management）的必要前提。本研究将ITS2核糖体DNA（ITS2 rDNA）与同型1 β微管蛋白（isotype-1 beta-tubulin）深度扩增子测序（deep amplicon sequencing）技术，应用于从野生山羊（feral goats）、同域分布绵羊和牛（sympatric sheep and cattle）的粪便（faeces）中采集的幼虫样本（larval samples）。研究结果验证了该方法的应用价值：首次从分子层面证实野生山羊可作为苯并咪唑类（benzimidazole）耐药泛宿主性线虫的储存宿主，并揭示了环纹背带线虫（Teladorsagia circumcincta）的一个隐存物种（cryptic species）。