Establishment of an antibody avidity test to differentiate vaccinated cattle from those naturally infected with Mycoplasma bovis
Establishment of an antibody avidity test to differentiate vaccinated cattle from those naturally infected with Mycoplasma bovis
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建立抗体亲和力测试以区分接种疫苗的牛与自然感染牛支原体的牛
DOI：
10.1016/j.tvjl.2014.10.032
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发表时间：
2015-01-01
影响因子：
2.2
通讯作者：
Guo, Aizhen
中科院分区：
文献类型：
--
作者：
Han, Xiaoxiao;Khan, Farhan Anwar;Guo, Aizhen
牛支原体是中国牛呼吸道疾病（BRD）的主要病原体，近年来已研制出牛支原体减毒活疫苗。本研究的目的是建立一种IgG亲和力试验来区分自然感染和接种疫苗的动物。在实验室中首次建立了间接ELISA (iELISA)，利用全细胞蛋白作为包衣抗原和实验感染牛的血清样本检测牛支原体特异性抗体。采用商用ELISA试剂盒作为参比标准，证实了iELISA的特异性和敏感性。kappa值为0.78(95%置信区间CI， 0.62, 0.93)，两个检验的一致性为92.0%（80/87）。在实验室iELISA的基础上，开发了硫氰酸钠（NaSCN）竞争性iELISA，用于检测IgG的亲和度，以相对亲和度指数（AI）表示。221只实验免疫和自然感染的动物被使用。其中包括36头免疫小牛，38头阴性对照小牛，37头自然感染小牛，87头状态未知的小牛，以及另外3头用于计时赛的免疫小牛。通过检测自然感染或免疫小牛的真阳性和阴性抗血清，Al临界值定义为70.4%。使用从实验动物采集的血清样本来确定内部NaSCN竞争性iELISA的诊断准确性。IgG亲和度试验灵敏度为96.0% (95% CI为80.5%,99.3%)，特异性为95.8% (95% CI为79.8%,99.3%)，成功地建立了作为区分接种疫苗动物与牛支原体感染动物的有价值的第一个试验。该试验可能是澄清牛支原体感染程度和评估暴露动物群体接种疫苗效果的有用工具。(C) 2014 Elsevier Ltd.版权所有。
Mycoplasma bovis is a major pathogen of bovine respiratory disease (BRD) in China and a live attenuated vaccine has recently been developed. This study aimed to establish an IgG avidity test to differentiate between naturally infected and vaccinated animals. An indirect ELISA (iELISA) was first established in the laboratory to detect antibodies specific to M. bovis using whole cell proteins as coating antigens and serum samples from experimentally infected cattle. The specificity and sensitivity of the iELISA was confirmed using a commercial ELISA kit as a reference standard. Both tests showed substantial agreement as indicated by a kappa value of 0.78 (95% confidence interval, CI, 0.62, 0.93), and an overall 92.0% (80/87) agreement between the two tests. Based on the laboratory iELISA, a sodium thiocyanate (NaSCN) competitive iELISA was then developed for the detection of IgG avidity, expressed as relative avidity index (AI).Two-hundred and one experimentally immunised and naturally infected animals were used. These comprised 36 immunised calves, 38 negative control calves, 37 naturally infected calves, 87 calves of unknown status, and an additional three immunised calves that were used for a time trial. By testing true positive and negative antisera from either naturally infected or immunised calves, the Al cut-off value was defined as 70.4%. The diagnostic accuracy of the in-house NaSCN competitive iELISA was determined using serum samples collected from the experimental animals. The IgG avidity test demonstrated 96.0% sensitivity (95% CI 80.5%, 99.3%) and 95.8% specificity (95% CI 79.8%, 99.3%), and was successfully established as a valuable first test for differentiating vaccinated animals from those infected with M. bovis. This test may be a useful tool for clarifying the magnitude of M. bovis infection and in assessing the efficacy of vaccination in exposed animal populations. (C) 2014 Elsevier Ltd. All rights reserved.