Establishing value/utility of thyroid hormone response as a biomarker for prediction of the resilience of swine following PRRSV infection

猪繁殖与呼吸综合征(PRRS)是世界范围内危害养猪业的重要疾病之一。孕期感染会导致流产，降低产仔数量和质量，而出生后感染会导致呼吸道疾病和免疫抑制。因此，该病对加拿大猪肉行业的健康、生产、猪的福利和环境足迹(需要更多母猪)具有重大影响。PRRS病毒进化迅速，与流感病毒相似，导致疫苗接种效果不到100%。即使接种了疫苗的动物也很容易被不同的病毒株再次感染。生产者可以采取昂贵的程序从他们的农场消除病毒，但农场通常在1-2年内再次感染。出于这些原因，其他控制方法是合理的。这项研究的首要目标是发现血液中测量的生物标记物，这些生物标记物将预测对PRRS的弹性。如果基因上有关联，就有可能选择对PRRS具有更强韧性的动物。加拿大和美国的研究人员将使用从过去的动物实验中收集的血清来研究两个生物标志物。使用存档样本降低了成本，提高了完成的速度。在安大略省猪肉公司赞助的第一阶段，将对不同年龄段的大约2200只动物的血清中的可溶性CD163进行测量。可溶性CD163是炎症的标志，也是PRRS病毒在动物免疫细胞中复制所必需的受体。在NSERC赞助的第二阶段，将测量大约4650头猪的血清中的甲状腺激素水平。这些样本包括与第一阶段相同的样本，加上额外的队列，以实现三项全基因组关联研究(GWAS)。甲状腺激素有许多与调节食欲、新陈代谢、生长和胎儿发育有关的功能。如果任何一个标记是可遗传的，我们的结果将显著改善加拿大猪群的健壮性，从而提高行业竞争力、生产率和福利。**

Porcine reproductive and respiratory syndrome (PRRS) is one of the most important diseases of pig production worldwide. Infection during pregnancy results in abortion and reduced litter size and quality, whereas infection after birth results in respiratory disease and immune suppression. Thus, the disease has a major impact on health, production, pig welfare and environmental footprint (more sows are required) in the Canadian pork industry. The PRRS virus evolves rapidly, similar to influenza virus, making vaccination less than 100% effective. Even vaccinated animals are prone to reinfection by different strains of virus. Producers can undertake costly procedures to eliminate the virus from their farms, but farms often become re-infected within 1-2 years. For these reasons, alternative methods of control are justified. The overarching objective of this research is to discover biomarkers measured in the blood that will predict resilience to PRRS. If genetically linked, it may be possible to select animals that have increased resilience to PRRS. Two biomarkers will be investigated using sera collected from past animal experiments conducted by researchers in Canada and the USA. Use of archived samples reduces the cost and increases the speed at which it can be completed. In Phase 1, sponsored by Ontario Pork, soluble CD163 will be measured in the serum of approximately 2,200 animals across various age groups. Soluble CD163 is a marker of inflammation and the requisite receptor used by PRRS virus to replicate in an animal's immune cells. In Phase 2, sponsored by NSERC, thyroxin hormone levels will be measured in the serum of approximately 4,650 pigs. These include the same samples as used for phase 1 plus additional cohorts to enable three genome wide association studies (GWAS). The thyroxin hormones have many functions related to regulation of appetite, metabolism, growth and fetal development. If either marker is heritable, our results will significantly improve the robustness of the Canadian swine herd, thereby improving industry competitiveness, productivity and welfare.**