一株牛源多动物链球菌致病性及基因组特性分析

Pathogenicity and genomic characteristics of a Streptococcus pluranimalium strain isolated from bovine

摘要:

【背景】多动物链球菌(Streptococcus pluranimalium，Sp)最早于1999年由Devriese等报道，是一种具有广泛宿主来源的潜在人畜共患病原体。目前的研究中，该菌种已从牛、羊、猪、肉鸡等多个物种的感染组织中被分离确认。然而，目前对其致病性、耐药性和基因组学等相关研究较少。【目的】从牛呼吸道分离鉴定一株Sp菌，分析其致病性及耐药性；通过基因组测序分析，明确其基因组的基本特征及部分毒力因子和耐药基因。【方法】从患病牛鼻拭子分离菌株并进行16S rRNA基因测序鉴定，开展对兔致病性试验和药敏试验；通过Illumina测序、组装以获取该菌株基因组一般特征信息，进行Swiss-Prot、NR、GO、COG、KEGG、CAZy、TCDB、Pfam数据库注释并分析基因功能，并通过PHI、VFDB、CARD数据库注释该菌株的毒力因子及耐药基因。【结果】分离到一株多动物链球菌Bov5，可引起兔肺组织肺间隔增厚及炎性细胞浸润；药敏试验结果显示其对林可霉素和克林霉素耐药，对链霉素中介；全基因组测序组装后确定其基因组大小为2 038 579 bp (2.04 Mb)，注释到的编码基因共计1 981个，注释到毒力因子100个，突变导致病原致病能力增强的基因28个，耐药相关基因83个。【结论】分离到一株具有较强致病性的牛源多动物链球菌，构建了菌株基因组框架图，挖掘出系列毒力和耐药相关基因，为进一步研究Sp致病基因和耐药基因奠定了基础。

Abstract:

[Background] Streptococcus pluranimalium was initially reported by Devriese et al. in 1999 as a potential zoonotic pathogen with a broad range of hosts. Although this pathogen has been isolated and identified from infected tissues of several species, including cattle, sheep, pigs, and broilers, there are few studies reporting its pathogenicity, antibiotic resistance, and genomics, which remain to be studied. [Objective] This study aims to identify a S. pluranimalium strain isolated from bovine respiratory tract and analyze its pathogenicity and antibiotic resistance. The basic characteristics of the genome and some virulence factors and antibiotic resistance genes were identified by genome sequencing. [Methods] Nasal swabs were collected from diseased cattle for identification of the pathogenic bacteria by 16S rRNA sequencing. Furthermore, the pathogenicity of the isolate in rabbits and the drug susceptibility of the strain were studied. Illumina sequencing and assembly were carried out to obtain an overview of the genome of the strain. Swiss-Prot, NR, GO, COG, KEGG, CAZy, TCDB, and Pfam were used for gene annotation and function analysis. PHI, VFDB and CARD were employed to annotate the virulence factors and drug resistance genes of the strain. [Results] S. pluranimalium Bov5 was successfully isolated, which induced pulmonary septal thickening and inflammatory cell infiltration in the rabbit lung tissue. The strain was resistant to lincomycin and clindamycin and showcased intermediate resistance to streptomycin. The genome size of the strain was determined to be 2 038 579 bp (2.04 Mb). A total of 1 981 coding genes were annotated, including 100 virulence factors, 28 genes conferring enhanced pathogenicity due to mutations, and 83 antibiotic resistance genes. [Conclusion] We isolated a bovine-derived S. pluranimalium strain with strong pathogenicity, constructed the genome framework of the strain, and mined the virulence and antibiotic resistance genes. The findings laid a foundation for further studying the pathogenic genes and antibiotic resistance genes of S. pluranimalium.