Kipp Kaylee R, Redman Elizabeth M, Luksovsky Joe L, Claussen Dani, Gilleard John S, Verocai Guilherme G
Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, USA.
Department of Comparative Biology and Experimental Medicine, Host-Parasite Interactions Program, Faculty of Veterinary Medicine, Hospital Drive, 3330, University of Calgary, Calgary, Alberta, Canada.
Int J Parasitol Drugs Drug Resist. 2025 Apr 14;28:100594. doi: 10.1016/j.ijpddr.2025.100594.
Bison production is a growing sector of the United States agriculture, with more consumers choosing bison products. Commercial bison are kept on smaller pastures and treated with anthelmintics for gastrointestinal nematodes (GIN) to maintain production. However, there is a lack of information regarding the GIN parasite communities in ranched bison or the extent of their resistance to anthelmintics. Our objectives were: i) to determine the GIN species present and the extent of resistance to the benzimidazole drug class in commercial bison herds in the southern US and ii) to assess age class differences in GIN species composition and BZ resistance. Composite coprocultures from bison in Texas (n = 14) and Oklahoma (n = 2), and individual bison of different age classes from a single ranch in central Texas (n = 43) were analyzed using ITS2 rDNA nemabiome metabarcoding to determine the trichostrongylid species composition. For both the composite and individual samples, the most common trichostrongylid species found were Haemonchus contortus, Haemonchus placei, and Ostertagia ostertagi. Among the known canonical isotype-1 β-tubulin BZ resistance polymorphisms (at codons 200, 198, 167), the 200Y (TTC > TAC) substitution was the most widespread across the two southern states, with a prevalence of 81.3 %. Other polymorphisms, such as 167Y (TTC > TAC) and 198L (GAA > TTA), were also detected, and both had prevalences of 62.5 %. Ostertagia ostertagi was found to have very high frequencies (overall mean frequency = 62.6 %; range = 28.3-100 %) of the 200Y (TTC > TAC) polymorphism in all age classes sampled. Overall, benzimidazole resistance polymorphisms were found at moderate to high frequency in the three major economically important GIN species in ranched bison in Texas and Oklahoma, suggesting a potential widespread distribution of benzimidazole resistance polymorphisms in the southern United States. This work has important implications for all other grazing livestock and illustrates the importance of early detection of anthelmintic resistance and the need for mitigation strategies.
野牛养殖是美国农业中一个不断发展的领域，越来越多的消费者选择野牛产品。商业化养殖的野牛被饲养在较小的牧场，并使用抗蠕虫药来治疗胃肠道线虫（GIN）以维持产量。然而，关于牧场饲养野牛体内的GIN寄生虫群落及其对驱虫药的耐药程度，目前缺乏相关信息。我们的目标是：i）确定美国南部商业化野牛群中存在的GIN种类及其对苯并咪唑类药物的耐药程度，以及ii）评估不同年龄组之间GIN种类组成和对苯并咪唑耐药性的差异。使用ITS2 rDNA线虫生物群落代谢条形码技术分析了来自德克萨斯州（n = 14）和俄克拉荷马州（n = 2）的野牛混合粪便培养物，以及来自德克萨斯州中部一个牧场的不同年龄组的个体野牛（n = 43），以确定毛圆科线虫的种类组成。对于混合样本和个体样本，最常见的毛圆科线虫种类是捻转血矛线虫、长刺血矛线虫和奥斯特他线虫。在已知的典型1型β -微管蛋白苯并咪唑耐药性多态性（密码子200、198、167处）中，200Y（TTC > TAC）替换在这两个南部州最为普遍，流行率为81.3%。还检测到了其他多态性，如167Y（TTC > TAC）和198L（GAA > TTA），两者的流行率均为62.5%。在所有采样的年龄组中，奥斯特他线虫的200Y（TTC > TAC）多态性频率都非常高（总体平均频率 = 62.6%；范围 = 28.3 - 100%）。总体而言，在德克萨斯州和俄克拉荷马州牧场饲养的野牛中，三种主要经济重要性的GIN种类对苯并咪唑的耐药性多态性频率处于中到高，这表明在美国南部苯并咪唑耐药性多态性可能广泛分布。这项工作对所有其他放牧家畜都具有重要意义，并说明了早期检测驱虫药耐药性的重要性以及制定缓解策略的必要性。
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