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.

中文翻译：

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个体和散装牛奶样品适合通过ELISA研究针对块状皮肤病疫苗接种的体液免疫反应。

使用针对血清和血浆进行验证的市售ELISA，检测抗己内毒素病毒的抗体变得更加容易。为了探索其对替代样品进行免疫学研究的适用性，本研究针对牛奶作为可通过非侵入性采样获得的样品基质。这项研究的样本是在没有LSD病毒传播的地区从针对LSD疫苗接种的奶牛中收集的。配对的血清和牛奶（个体和散装）样品通过ELISA进行了测试，未修改牛奶样品的样品孵育时间。为了评估测试特异性，将德国一家牛奶仓库中的352份牛奶样品用作阴性对照。进行受体工作特征分析以确定尤登指数，并确定最合适的临界值以获得最大特异性。从154份来自塞尔维亚的分析血清样品中，ELISA检测出75份呈阳性。使用Youden标准，牛奶样品ELISA测试的灵敏度和特异性达到88％至91％的值。为了获得最大的特异性，确定了10的临界值。该临界值用于进一步分析。使用血清方案，在154份牛奶样品中，有38份被检测为阳性，经修改的方案，阳性检测到的牛奶样品数量增加到48份。来自德国的牛奶样品反应为阴性，但使用改良方案的两个样品具有临界结果。统计学差异显着（p <0。在两个孵育方案之间观察到05）。从散装牛奶样品（2–10个人的池）中检测到LSD特异性抗体会降低动物个体样品的灵敏度。结果表明，使用IDvet上的市售ELISA检测牛奶样品中的Capripoxvirus特异性抗体是可行的，并且可以代表LSDV监测程序的有用工具。