Dürlinger Sophie, Kreutzmann Heinrich, Unterweger Christine, Martin Vera, Hamar Flora, Knecht Christian, Auer Angelika, Dimmel Katharina, Rümenapf Till, Griessler Alfred, Voglmayr Thomas, Maurer Roland, Oppeneder Alexander, Ladinig Andrea
Clinical Department for Farm Animals and Food System Science, Clinical Centre for Population Medicine in Fish, Pig and Poultry, University of Veterinary Medicine Vienna, Veterinaerplatz 1, 1210, Vienna, Austria.
GD Animal Health Service, P.O. Box 9, 7400 AA, Deventer, The Netherlands.
Porcine Health Manag. 2024 May 19;10(1):18. doi: 10.1186/s40813-024-00370-0.
Infection with porcine reproductive and respiratory syndrome virus (PRRSV) leads to significant economic losses worldwide. One of the initial measures following an outbreak is to stabilise the herd and to prevent vertical transmission of PRRSV. The objective of this study was to detect PRRSV in different sampling material, both in an experimental model and on a commercial piglet producing farm, with a focus on evaluating the suitability of tongue fluid samples.
In the experimental model, PRRSV negative pregnant gilts were infected with PRRSV-1 AUT15-33 on gestation day 85 and necropsy of gilts and foetuses was performed three weeks later. 38.3% of individual foetal serum and 39.4% of individual foetal thymus samples were considered PRRSV RT-qPCR positive. Tongue fluids from individual foetuses showed a 33.0% positivity rate. PRRSV RNA was detected in all but one sample of litter-wise pooled processing fluids and tongue fluids. In the field study, the investigated farm remained PRRSV positive and unstable for five consecutive farrowing groups after the start of the sampling process. Tongue fluid samples pooled by litter in the first investigated farrowing group had a 54.5% positivity rate, with the overall highest viral load obtained in the field study. In this farrowing group, 33.3% of investigated litter-wise pooled processing fluid samples and all investigated serum samples (pools of 4-6 individuals, two piglets per litter) were considered positive. Across all investigated farrowing groups, tongue fluid samples consistently showed the highest viral load. Moreover, tongue fluid samples contained the virus in moderate amounts for the longest time compared to the other investigated sampling material.
It can be concluded that the viral load in individual foetuses is higher in serum or thymus compared to tongue fluid samples. However, litter-wise pooled tongue fluid samples are well-suited for detecting vertical transmission within the herd, even when the suspected prevalence of vertical transmission events is low.
猪繁殖与呼吸综合征病毒（PRRSV）感染在全球范围内造成重大经济损失。疫情爆发后的初步措施之一是稳定猪群并防止PRRSV的垂直传播。本研究的目的是在实验模型和商业仔猪生产农场中，检测不同采样材料中的PRRSV，重点是评估舌液样本的适用性。
在实验模型中，PRRSV阴性的妊娠后备母猪在妊娠第85天感染PRRSV-1 AUT15-33，三周后对母猪和胎儿进行剖检。38.3%的单个胎儿血清样本和39.4%的单个胎儿胸腺样本被认为PRRSV RT-qPCR检测呈阳性。单个胎儿的舌液样本阳性率为33.0%。在除一份外的所有按窝收集的加工液和舌液样本中均检测到PRRSV RNA。在实地研究中，采样过程开始后，被调查农场在连续五个产仔组中PRRSV检测均呈阳性且不稳定。在第一个被调查的产仔组中，按窝收集的舌液样本阳性率为54.5%，是实地研究中获得的总体最高病毒载量。在这个产仔组中，33.3%的被调查按窝收集的加工液样本和所有被调查的血清样本（4 - 6头个体的混合样本，每窝两只仔猪）被认为呈阳性。在所有被调查的产仔组中，舌液样本始终显示出最高的病毒载量。此外，与其他被调查的采样材料相比，舌液样本中病毒含量适中的持续时间最长。
可以得出结论，与舌液样本相比，单个胎儿血清或胸腺中的病毒载量更高。然而，即使垂直传播事件的疑似患病率较低，按窝收集的舌液样本也非常适合检测猪群内的垂直传播。
