Department of Infectious Diseases of Animals and Diseases of Bees, University of Belgrade, Faculty of Veterinary Medicine, Blvd. Oslobodjenja 18, Belgrade, 11000, Serbia.
Virology Department, Institute of Veterinary Medicine of Serbia, Vojvode Toze 14, Belgrade, 11000, Serbia.
Virol J. 2020 Mar 5;17(1):28. doi: 10.1186/s12985-020-01298-x.
The detection of antibodies against capripoxvirus has become easier with a commercially available ELISA validated for serum and plasma. In order to explore its suitability for immunological investigations on alternative samples, this study targeted milk as sample matrix available through non-invasive sampling.
Samples for this study were collected from dairy cows vaccinated against LSD in an area without reported LSD virus circulation. Paired serum and milk (individual and bulk) samples were tested by ELISA without and with modifications of the sample incubation time for the milk samples. For the evaluation of the test specificity, 352 milk samples from a milk repository in Germany were used as negative control. Receiver operating characteristic analysis was performed for determination of the Youden index and determination of the most suitable cut-off value for maximum specificity.
From 154 analyzed serum samples from Serbia, 75 were detected as positive in the ELISA. Sensitivity and specificity of the ELISA test for milk samples reached values of 88 to 91% using Youden criteria. A cut-off of 10 was determined aiming for maximum specificity. This cut-off value was used for further analysis. Using the protocol for serum, out of 154 milk samples, 38 were detected as positive, number of positive detected milk samples increase up to 48 with modified protocol. Milk samples from Germany reacted negative, except two samples that had borderline results using modified protocol. Significant statistical difference (p < 0.05) was observed between two incubation protocols. The detection of LSD-specific antibodies from bulk milk samples (pools of 2-10 individuals) came along with a reduced sensitivity over the sample of individual animals.
Results show that the detection of capripoxvirus specific antibodies in milk samples using the commercially available ELISA from IDvet is feasible and can represent a helpful tool for LSDV monitoring programs.
由于一种可商购的 ELISA 已被验证可用于血清和血浆，因此检测羊痘病毒抗体变得更加容易。为了探索其在替代样本免疫研究中的适用性，本研究将牛奶作为可通过非侵入性采样获得的样本基质。
本研究的样本来自在没有 LSD 病毒报告的地区接种 LSD 疫苗的奶牛。使用 ELISA 对血清和牛奶（个体和批量）样本进行检测，同时对牛奶样本的孵育时间进行了修改。为了评估测试的特异性，使用来自德国牛奶库的 352 份牛奶样本作为阴性对照。进行了接收者操作特征分析，以确定 Youden 指数并确定最大特异性的最佳截断值。
在来自塞尔维亚的 154 份分析血清样本中，有 75 份在 ELISA 中被检测为阳性。使用 Youden 标准，ELISA 测试对牛奶样本的敏感性和特异性达到 88%至 91%。为了获得最大特异性，确定了 10 的截断值。该截断值用于进一步分析。使用血清方案，在 154 份牛奶样本中，有 38 份被检测为阳性，使用改良方案，阳性检测到的牛奶样本数量增加到 48 份。来自德国的牛奶样本反应为阴性，除了两份使用改良方案的样本结果为边界值。两种孵育方案之间存在显著的统计学差异（p<0.05）。从批量牛奶样本（2-10 个体的样本）中检测到 LSD 特异性抗体，其敏感性比个体动物样本有所降低。
结果表明，使用 IDvet 市售 ELISA 从牛奶样本中检测羊痘病毒特异性抗体是可行的，并且可以成为 LSDV 监测计划的有用工具。
