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Abstract：
This study aimed to enhance our understanding of the agreement between two sampling methods for the detection of bovine respiratory disease (BRD) pathogens in calves using high-throughput real-time qPCR (ht-RT-qPCR). In total, 233 paired nasal swab (NS) and non-endoscopic bronchoalveolar lavage (nBAL) samples were collected from 152 calves from 12 Danish cattle herds. In 202 of the observations, the calves were examined using a standardized clinical protocol. Samples were tested for three viruses (bovine respiratory syncytial virus, bovine corona virus, and influenza D virus) and six bacteria (Histophilus somni, Mannheimia haemolytica, Mycoplasma bovis, Mycoplasma species, Pasteurella multocida, and Truepurella pyogenes). The results showed age-related differences in disease and pathogen occurrence, with the highest detection rates in calves aged 35 days or older. Poor to moderate agreement was found between the NS and nBAL results. The presence of Mannheimia haemolytica in both NS and nBAL in younger calves and in nBAL in older calves was associated with clinical BRD. There was a potential link between BRD and influenza D virus in older calves, although it was only found in one herd in a small sample size. Overall, NS was a relatively poor predictor of pathogens in the lower respiratory tract. The present study confirms the complexity of pathogen detection in BRD, with marked influences of age and the sampling method on pathogen detection and disease associations.
摘要：
本研究旨在增强我们对使用高通量实时qPCR（ht-RT-qPCR）检测小牛呼吸道疾病（BRD）病原体的两种采样方法之间的协议的理解。总的来说,从12只丹麦牛群的152只小牛中收集了233个配对的鼻拭子（NS）和非内窥镜支气管肺泡灌洗（nBAL）样品。在202个观察中，使用标准化的临床方案对小牛进行了检查.对样品进行了三种病毒（牛呼吸道合胞病毒，牛冠状病毒,和D型流感病毒）和六种细菌（嗜血杆菌，Mannheimia溶血病,牛支原体,支原体物种，多杀性巴氏杆菌,和Truepurellapyogenes）。结果显示疾病和病原体发生的年龄相关差异，在35天或以上的小牛中检出率最高。在NS和nBAL结果之间发现了差到中等的一致性。在年轻小牛的NS和nBAL中以及在老年小牛的nBAL中，溶血曼海姆菌的存在与临床BRD有关。BRD和老年小牛的D型流感病毒之间存在潜在的联系，尽管它只在一个小样本中发现。总的来说,NS是下呼吸道病原体相对较差的预测指标。本研究证实了BRD病原体检测的复杂性，年龄和采样方法对病原体检测和疾病关联有显著影响。
