Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 1870 Frederiksberg C, Denmark.
Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 1870 Frederiksberg C, Denmark.
J Dairy Sci. 2018 Aug;101(8):7383-7396. doi: 10.3168/jds.2017-14340. Epub 2018 May 16.
Mycoplasma bovis is an important pathogen causing disease and substantial economic losses in cattle. However, knowledge of the dynamics of antibody responses in individual cows in the face of an outbreak is currently extremely limited. The use of commercial antibody tests to support clinical decision-making and for surveillance purposes is therefore challenging. Our objective was to describe the dynamics of M. bovis antibody responses in 4 Danish dairy herds experiencing an acute outbreak of M. bovis-associated disease, and to compare the antibody dynamics between dairy cows with different disease manifestations. A total of 120 cows were examined using a standardized clinical protocol and categorized into 4 disease groups: "mastitis," "systemic," "nonspecific," and "none." Paired blood and milk samples were collected and tested using a commercial M. bovis antibody-detecting ELISA. Plots of raw data and generalized additive mixed models with cow and herd as random effects were used to describe serum and milk antibody dynamics relative to the estimated time of onset of clinical disease. Cows with mastitis had high optical density measurement (ODC%) of antibodies in both milk and serum at disease onset. The estimated mean ODC% in milk was below the manufacturer's cut-off for the other groups for the entire study period. The estimated mean serum ODC% in the "systemic" group was high at onset of disease and stayed above the cut-off until 65 d after disease onset. However, the lower 95% confidence interval (CI) for the mean ODC% was only above the manufacturer's cut-off between 7 and 17 d after onset of disease. The CI of the "systemic" and "none" groups did not overlap at any time between the day of disease onset and 65 d after disease onset, and the estimated mean ODC% for both the "nonspecific" and "none" groups were generally below the cut-off for the majority of the study period. In conclusion, the serum antibody responses were highly dynamic and showed a high level of variation between individual cows. This strongly suggests that serology is unlikely to be useful for individual diagnosis of M. bovis-associated disease in dairy cows. However, it might still be useful for herd- or group-level diagnosis. Antibodies in milk were only increased in cows with M. bovis mastitis, indicating that milk antibody measurements only have diagnostic utility for cows with mastitis.
牛支原体是一种重要的病原体，可导致牛只患病并造成重大经济损失。然而，目前对于个体牛在暴发疫情时的抗体反应动态知之甚少。因此，商业抗体检测用于支持临床决策和监测具有挑战性。我们的目标是描述丹麦 4 个奶牛场在急性牛支原体相关疾病暴发期间牛支原体抗体反应的动态，并比较具有不同疾病表现的奶牛的抗体动态。使用标准化临床方案对 120 头奶牛进行检查，并将其分为 4 个疾病组：“乳腺炎”、“系统性”、“非特异性”和“无”。采集配对的血液和牛奶样本，并使用商业牛支原体抗体检测 ELISA 进行检测。使用原始数据图和带有牛和牛群作为随机效应的广义加性混合模型来描述血清和牛奶抗体相对于临床疾病发病时间的动态。乳腺炎奶牛在疾病发病时牛奶和血清中的抗体光密度测量值（ODC%）较高。在整个研究期间，估计的牛奶 OD C%均值低于制造商规定的其他组的截止值。“系统性”组的估计血清 ODC%在疾病发病时较高，并且在疾病发病后 65 天内保持在截止值以上。然而，均值 ODC%的较低 95%置信区间（CI）仅在发病后 7 至 17 天之间高于制造商的截止值。在疾病发病之日至发病后 65 天之间的任何时间，“系统性”和“无”组的 CI 都没有重叠，并且“非特异性”和“无”组的估计平均 ODC%在研究期间的大部分时间都低于截止值。总之，血清抗体反应高度动态，个体牛之间存在很大的变异性。这强烈表明血清学不太可能用于个体奶牛牛支原体相关疾病的诊断。然而，它可能仍然对群体或群体水平的诊断有用。牛奶中的抗体仅在患有牛支原体乳腺炎的奶牛中增加，表明牛奶抗体测量仅对乳腺炎奶牛具有诊断效用。
