Austin Davis Biologics, Unit 1 Denfield Lodge, Great Addington, NN14 4BL, UK.
College of Health and Life Sciences, Aston University, Birmingham, B4 7ET, UK.
Int J Parasitol. 2024 Jan;54(1):23-32. doi: 10.1016/j.ijpara.2023.07.001. Epub 2023 Aug 1.
Cyathostomins are ubiquitous equine nematodes. Infection can result in larval cyathostominosis due to mass larval emergence. Although faecal egg count (FEC) tests provide estimates of egg shedding, these correlate poorly with burden and provide no information on mucosal/luminal larvae. Previous studies describe a serum IgG(T)-based ELISA (CT3) that exhibits utility for detection of mucosal/luminal cyathostomins. Here, this ELISA is optimised/validated for commercial application using sera from horses for which burden data were available. Optimisation included addition of total IgG-based calibrators to provide standard curves for quantification of antigen-specific IgG(T) used to generate a CT3-specific 'serum score' for each horse. Validation dataset results were then used to assess the optimised test's performance and select serum score cut-off values for diagnosis of burdens above 1000, 5000 and 10,000 cyathostomins. The test demonstrated excellent performance (Receiver Operating Characteristic Area Under the Curve values >0.9) in diagnosing infection, with >90% sensitivity and >70% specificity at the selected serum score cut-off values. CT3-specific serum IgG(T) profiles in equines in different settings were assessed to provide information for commercial test use. These studies demonstrated maternal transfer of CT3-specific IgG(T) in colostrum to newborns, levels of which declined before increasing as foals consumed contaminated pasture. Studies in geographically distinct populations demonstrated that the proportion of horses that reported as test positive at a 14.37 CT3 serum score (1000-cyathostomin threshold) was associated with parasite transmission risk. Based on the results, inclusion criteria for commercial use were developed. Logistic regression models were developed to predict probabilities that burdens of individuals are above defined thresholds based on the reported serum score. The models performed at a similar level to the serum score cut-off approach. In conclusion, the CT3 test provides an option for veterinarians to obtain evidence of low cyathostomin burdens that do not require anthelmintic treatment and to support diagnosis of infection.
Cyathostomins 是无处不在的马属线虫。感染会导致幼虫 cyathostominosis，因为大量幼虫出现。虽然粪便卵计数 (FEC) 测试提供了卵脱落的估计，但这些与负担相关性差，并且不能提供关于粘膜/腔幼虫的信息。以前的研究描述了一种基于血清 IgG(T) 的 ELISA (CT3)，该 ELISA 对检测粘膜/腔 cyathostomins 具有实用性。在这里，使用有负担数据的马的血清对该 ELISA 进行了商业应用的优化/验证。优化包括添加总 IgG 校准物，为用于生成每个马的 CT3 特异性“血清评分”的抗原特异性 IgG(T) 提供标准曲线。然后使用验证数据集结果评估优化测试的性能，并选择血清评分截断值以诊断负担超过 1000、5000 和 10,000 个 cyathostomins。该测试在诊断感染方面表现出出色的性能（接受者操作特征曲线下面积值>0.9），在选定的血清评分截断值下，敏感性>90%，特异性>70%。评估了不同环境中马的 CT3 特异性血清 IgG(T) 谱，为商业测试提供了信息。这些研究表明，CT3 特异性 IgG(T) 在初乳中从母体转移到新生儿，其水平在幼驹消耗受污染的牧场之前下降，然后增加。在地理位置不同的人群中进行的研究表明，报告在 14.37 CT3 血清评分（1000-cyathostomin 阈值）处为阳性的马的比例与寄生虫传播风险相关。根据结果，制定了商业用途的纳入标准。开发了逻辑回归模型，以根据报告的血清评分预测个体负担超过定义阈值的概率。这些模型的表现与血清评分截断值方法相似。总之，CT3 测试为兽医提供了一种选择，以获得不需要驱虫治疗的低 cyathostomin 负担的证据，并支持感染的诊断。
