致脑膜炎多杀性巴氏杆菌的分离鉴定及全基因组重测序

Isolation and Genomic Characterization of a Meningitis Causing Pasteurella multocida

旨在了解致脑膜炎多杀性巴氏杆菌的生物学特性及其引起脑部感染的生物学基础。本研究从有神经症状的病死猪脑组织中分离鉴定1株多杀性巴氏杆菌SD001,对其开展血清杀菌试验、胞内存活试验、小鼠感染试验,并利用纳米孔测序技术对其进行全基因组测序。SD001相对于猪其他器官中分离的多杀性巴氏杆菌而言表现出更强的抗血清杀菌的能力,其在小鼠巨噬细胞内存活的能力也较强。小鼠感染试验显示,相同剂量的细菌经血液感染后,SD001在小鼠血液和脑组织中的载菌量显著高于猪肺炎型多杀性巴氏杆菌(P≤0.01),并且SD001造成了小鼠脑组织发生炎症等病理损伤,提示SD001可能造成血流感染并引起小鼠脑膜炎。纳米孔测序显示,SD001的全基因组大小约为2.45 Mb,平均GC含量为40.25%,编码2281个蛋白以及77个RNA;SD001基因组中含有2条CRISPR结构、5个基因岛、7条前噬菌体序列;毒力基因预测结果显示,SD001含有233个毒力基因;基因分型结果显示,SD001为荚膜:LPS:MLST基因型A:L6:ST10。SD001感染可以引起脑膜炎,其较强的抗血清杀菌能力以及能形成血流感染的能力可能是SD001引起脑部感染的重要原因,在兽医临床关于中枢神经系统感染的诊断中应该纳入多杀性巴氏杆菌感染的可能性。

This study was designed to investigate the biological characteristics of a meningitis causing Pasteurella multocida and the biological basis for this bacterium causing brain infections.Serum bactericidal tests,intracellular survival tests,mouse infection tests,and nanopore sequencing were performed on a P.multocida strain SD001 which was isolated from the brain of a pig with neurological symptoms.Results were as follows:Compared to those of P.multocida isolates from the other organs of pigs,SD001 displayed a stronger anti-serum bactericidal capacity,and a stronger capacity of surviving in mouse macrophages.In mouse models,SD001 formed a higher bacterial load in both blood and brain than a pneumonic P.multocida strain at the same time points post challenge,and the challenge of SD001 led to inflammatory and other pathological damages in the experimental mice.These findings suggest that SD001 may cause bloodstream infections and meningitis animals.Results from nanopore sequencing revealed that the complete genome sequence of SD001 was 2.45 Mb in size,with an average GC content of 40.25%.The complete genome of SD001 encoded 2281 putative proteins and 77 RNAs.It also contained two CRISPR sequences,five genomic islands,seven prophages,and 233 virulence factor encoding genes.Genotyping using the complete genome sequence showed that SD001 belonged to capsular:LPS:MLST type A:L6:ST10.SD001 infection could cause meningitis and its strong capacity of anti-serum bactericidal activity as well as inducing bloodstream infection may confer the bacterium capacity of causing brain infections.P.multocida infection should be considered for the diagnosis of brain infections in veterinary clinical settings.