猪繁殖与呼吸综合征病毒(PRRSV)继续挑战美国和世界大部分地区的猪生产。猪群中有效的PRRSV监测可能具有挑战性,特别是因为该病毒可以持续并维持非常低的流行率。尽管断奶年龄猪是繁殖群中PRRSV监测的战略亚群,很少的样本类型已经被验证和表征为监测这个亚群。本研究的目的,因此,比较血清中PRRSVRNA的检出率,口腔拭子(OS),鼻拭子(NS),耳静脉血拭子(ES),和从断奶年龄的猪获得的家庭口腔液(FOF),并评估产仔水平的汇集对PRRSVRNA的逆转录定量聚合酶链反应(RT-qPCR)检测的影响。
■选择了美国中西部的三个合格的PRRSV阳性牛群进行本研究。对55窝的666头猪进行了血清采样,NS,ES,操作系统,和FOF。分别对这些样品和拭子的垫料水平池进行RT-qPCR测试。每个拭子样品类型的凋落物级池通过组合从一窝猪中取出的每个拭子的相等体积来制备。
■分布在22窝的96只仔猪血清中的PRRSVRT-qPCR阳性,分布在15窝中的80只仔猪在ES上呈阳性,分布在17窝中的80只仔猪OS呈阳性,分布在14窝的72只仔猪在NS上呈阳性。科恩的kappa分析显示,所有配对的ES之间几乎是完美的一致,操作系统,NS,和血清比较()。血清RT-qPCR循环阈值(Ct)强烈预测拭子样品中的PRRSV检测。在ES-中PRRSV检测的概率≥95%,OS-,当阳性拭子样本比例≥23%时,NS池,≥27%,≥26%,分别。
■ES,NS,和OS可作为RT-qPCR检测断奶猪PRRSVRNA的监测样本。通过血清采样的仔猪的最小数量,ES,操作系统,当PRRSV患病率≥10%时,NS对检测≥1只感染仔猪的信心分别为30、36、36和40。
UNASSIGNED: The porcine reproductive and respiratory syndrome virus (PRRSV) continues to challenge swine production in the US and most parts of the world. Effective PRRSV surveillance in swine herds can be challenging, especially because the virus can persist and sustain a very low prevalence. Although weaning-age pigs are a strategic subpopulation in the surveillance of PRRSV in breeding herds, very few sample types have been validated and characterized for surveillance of this subpopulation. The objectives of this study, therefore, were to compare PRRSV RNA detection rates in serum, oral swabs (OS), nasal swabs (NS), ear-vein blood swabs (ES), and family oral fluids (FOF) obtained from weaning-age pigs and to assess the effect of litter-level pooling on the reverse transcription-quantitative polymerase chain reaction (RT-qPCR) detection of PRRSV RNA.
UNASSIGNED: Three eligible PRRSV-positive herds in the Midwestern USA were selected for this study. 666 pigs across 55 litters were sampled for serum, NS, ES, OS, and FOF. RT-qPCR tests were done on these samples individually and on the litter-level pools of the swabs. Litter-level pools of each swab sample type were made by combining equal volumes of each swab taken from the pigs within a litter.
UNASSIGNED: Ninety-six piglets distributed across 22 litters were positive by PRRSV RT-qPCR on serum, 80 piglets distributed across 15 litters were positive on ES, 80 piglets distributed across 17 litters were positive on OS, and 72 piglets distributed across 14 litters were positive on NS. Cohen\'s kappa analyses showed near-perfect agreement between all paired ES, OS, NS, and serum comparisons (). The serum RT-qPCR cycle threshold values (Ct) strongly predicted PRRSV detection in swab samples. There was a ≥ 95% probability of PRRSV detection in ES-, OS-, and NS pools when the proportion of positive swab samples was ≥ 23%, ≥ 27%, and ≥ 26%, respectively.
UNASSIGNED: ES, NS, and OS can be used as surveillance samples for detecting PRRSV RNA by RT-qPCR in weaning-age pigs. The minimum number of piglets to be sampled by serum, ES, OS, and NS to be 95% confident of detecting ≥ 1 infected piglet when PRRSV prevalence is ≥ 10% is 30, 36, 36, and 40, respectively.