Abstract：
Mannheimia haemolytica is known as one of the major bacterial contributors to Bovine Respiratory Disease (BRD) syndrome. This study sought to establish a novel species-specific PCR to aid in identification of this key pathogen. As well, an existing multiplex PCR was used to determine the prevalence of serovars 1, 2 or 6 in Australia. Most of the 65 studied isolates originated from cattle with a total of 11 isolates from small ruminants. All problematic field isolates in the identification or serotyping PCRs were subjected to whole genome sequencing and bioinformatic analysis. The field isolates were also subjected to rep-PCR fingerprinting. A total of 59 out of the 65 tested isolates were conformed as M. haemolytica by the new species-specific PCR which is based on the rpoB gene. The confirmed M. haemolytica field isolates were assigned to serovars 1 (24 isolates), 2 (seven isolates) and 6 (26 isolates) while two of the isolates were negative in the serotyping PCR. The two non-typeable isolates were assigned to serovar 7 and 14 following whole genome sequencing and bioinformatic analysis. The rep-PCR typing resulted in five major clusters with serovars 1 and 6 often within the same cluster. The M. haemolytica-specific PCR developed in this work was species specific and should be a valuable support for frontline diagnostic laboratories. The serotyping results support the relative importance of serovars 1 and 6 in bovine respiratory disease.
摘要：
已知溶血曼海姆菌是牛呼吸道疾病(BRD)综合征的主要细菌贡献者之一。这项研究试图建立一种新的物种特异性PCR来帮助鉴定这种关键病原体。同样,现有的多重PCR用于确定澳大利亚血清变型1,2或6的流行率.所研究的65个分离株中的大多数来自牛，共有11个来自小反刍动物。对鉴定或血清分型PCR中的所有有问题的现场分离株进行全基因组测序和生物信息学分析。野外分离株也进行了rep-PCR指纹分析。通过基于rpoB基因的新物种特异性PCR,在65个测试的分离物中总共有59个被证实为溶血分枝杆菌。已确认的溶血分枝杆菌田间分离株被分配到血清变型1（24个分离株），2（7个分离株）和6（26个分离株），而其中2个分离株在血清分型PCR中呈阴性。在全基因组测序和生物信息学分析后，将两个不可分型的分离株分配到血清型7和14。rep-PCR分型导致五个主要簇，其中血清变型1和6通常在同一簇内。在这项工作中开发的溶血分枝杆菌特异性PCR是物种特异性的，应该是一线诊断实验室的宝贵支持。血清分型结果支持血清变型1和6在牛呼吸道疾病中的相对重要性。
