David K, Dittmar K, Heenemann K, Reiner G, Donat K
Thüringer Tierseuchenkasse AdöR, Tiergesundheitsdienst, Jena, Deutschland.
Universität Leipzig, Veterinärmedizinische Fakultät, Zentrum für Infektionsmedizin, Institut für Virologie, Deutschland.
Schweiz Arch Tierheilkd. 2021 Jul;163(7):471-484. doi: 10.17236/sat00308.
Saliva samples from chewing ropes are a reliable diagnostic of porcine reproductive and respiratory syndrome virus (PRRSV) infections. The aim of this study was to test whether saliva samples taken with saliva swabs (cotton swabs and GenoTube Livestock) or with chewing ropes are suitable for monitoring PRRSV in unsuspicious farms, this means to detect a prevalence of 20% infected animals with a 95% probability. Saliva samples were collected from 12-16 pens in five pig farms by using a chewing rope for collective samples and by individual saliva swaps from five randomly selected animals per pen. A total of 291 animals from 58 pens in four study farms and 60 animals from 12 pens in one control farm were collected. The samples were taken from all age categories. According to the current monitoring system the analysis of five individual serum samples from the same pens served as the reference method for the relative sensitivity of the saliva samples. Serum and chewing rope samples were tested by ELISA for antibodies. Two different systems were used for the serum samples. Chewing ropes, saliva swabs (GenoTube Livestock) and serum samples were examined for virus genomes using a nested reverse-transcriptase PCR and a commercial real-time reverse-transcriptase PCR kit. Cohen's Kappa was used as a measure of agreement. PRRSV antibodies were detected in the chewing ropes of 44 pens and in the serum samples of only 34 pens. Viral RNA was found in 13 (chewing ropes), respectively 16 pens (serum samples). Saliva swabs (GenoTube Livestock) showed a lower relative sensitivity of 20.00% compared to serum samples. The agreement of the two serum analysis was very good for the ELISAs (κ = 0,911), and moderate for the PCR (κ = 0,706). The comparison of the chewing rope method with the analysis of the serum samples advocates this method as a suitable supplementary monitoring tool in PRRSV unsuspicious pig farms. Easy handling and lower examination costs of the chewing rope method allow higher testing frequency and would therefore improve the monitoring system. However, they are not an alternative to serum samples. Sampling with saliva swabs is unsuitable.
咀嚼绳采集的唾液样本是猪繁殖与呼吸综合征病毒（PRRSV）感染的可靠诊断样本。本研究的目的是测试用唾液拭子（棉签和GenoTube Livestock）或咀嚼绳采集的唾液样本是否适用于在无疫情猪场监测PRRSV，即检测出感染动物患病率为20%且概率为95%。通过使用咀嚼绳采集集体样本，并从每栏中随机选取的5只动物个体采集唾液拭子，从5个猪场的12 - 16个猪栏中采集唾液样本。在4个研究猪场的58个猪栏中总共采集了291只动物的样本，在1个对照猪场的12个猪栏中采集了60只动物的样本。样本取自所有年龄组。根据当前监测系统，对来自同一猪栏的5份个体血清样本进行分析作为唾液样本相对敏感性的参考方法。血清和咀嚼绳样本通过ELISA检测抗体。血清样本使用了两种不同的系统。使用巢式逆转录PCR和商业实时逆转录PCR试剂盒对咀嚼绳、唾液拭子（GenoTube Livestock）和血清样本检测病毒基因组。Cohen's Kappa用于衡量一致性。在44个猪栏的咀嚼绳中检测到PRRSV抗体，而在血清样本中仅在34个猪栏中检测到。分别在13个（咀嚼绳）和16个猪栏（血清样本）中发现病毒RNA。与血清样本相比，唾液拭子（GenoTube Livestock）的相对敏感性较低，为20.00%。两种血清分析方法在ELISA方面一致性非常好（κ = 0.911），在PCR方面一致性中等（κ = 0.706）。咀嚼绳方法与血清样本分析的比较表明，该方法是PRRSV无疫情猪场合适的补充监测工具。咀嚼绳方法操作简便且检测成本较低，可实现更高的检测频率，因此可改善监测系统。然而，它们不能替代血清样本。用唾液拭子采样不合适。
