携带89K样毒力岛的猪链球菌ST665型与ST107型临床菌株的基因组及致病分析  

Investigation the genomic and pathogenicity characteristics of streptococcus suis ST665 and ST107 clinical strains harboring 89K-like pathogenicity islands

作　　者：康娓铭 王鸣柳[2] 王建平[1] 张西燕 吴宗福 郑翰[1] Kang Weiming;Wang Mingliu;Wang Jianping;Zhang Xiyan;Wu Zongfu;Zheng Han(National Institute for Communicable Disease Control and Prevention,Chinese Center for Disease Control and Prevention,Beijing 102206,China;Guangxi Zhuang Autonomous Region Center for Disease Prevention and Control,Nanning 530028,Guangxi,China;College of Veterinary Medicine,Nanjing Agricultural University,OIE Reference Lab for Swine Streptococcosis,Nanjing 210095,Jiangsu,China)

机构地区：[1]中国疾病预防控制中心传染病预防控制所,北京102206 [2]广西壮族自治区疾病预防控制中心,广西南宁530028 [3]南京农业大学动物医学院,农业部动物细菌学重点实验室,江苏南京210095

出　　处：《疾病监测》2024年第5期622-628,共7页Disease Surveillance

基　　金：传染病预防控制国家重点实验室面上项目(No.2022SKLID208);国家科技重大专项(No.2017ZX10303405-002)。

摘　　要：目的明确89K样毒力岛(PAI)的基因组特征及其在猪链球菌致病及耐药传播方面的作用。方法通过生物信息学方法分析89K样PAIs的基因组特征;通过接合实验比较两种89K样PAIs的转移能力;采用最小抑菌浓度法测定临床分离株及接合子的耐药谱;通过C57BL/6小鼠和斑马鱼感染模型分别评估两个临床菌株及其89K样PAIs的接合子的致病性。结果携带89K样PAIs的猪链球菌临床菌株GX54和GX82的序列型(ST)分别为ST665和ST107。菌株GX54携带的PAI大小为75Kb,在核苷酸水平上与ST7流行型菌株携带的89K PAI具有99.21%的相似性和79.00%的覆盖率,而菌株GX82携带的PAI大小为87Kb,与89K PAI具有98.80%的相似性和86.00%的覆盖率。这两个PAIs的插入位点与89K PAI相同,均位于rplL位点,且PAIs的两端均含有一段15 bp的att序列(5’-TTATTTAAGAGTAAC-3’)。此外,这两个PAIs均具有完整的模块化结构,包含完整的NisK-NisR样双组分信号转导系统和IV型分泌系统(T4SS)。而在SalR-SalK样双组分信号转导系统中,仅SalR基因保持完整,SalK基因发生错义突变。与89K PAI相比,本研究中的两个PAIs在基因组成上呈现出一定的差异。75K PAI插入了4个基因,包括两个假定蛋白基因和两个耐药基因tet(O)和erm(B)。而87K PAI则插入了12个基因,主要涉及编码与质粒相关的重组酶和假基因,以及与耐药相关的cat、tet(L)、erm(B)基因。此外,还包括编码转座酶、拓扑异构酶等基因。菌株GX54携带的75K PAI的转移频率为4.61×10−5,显著高于菌株GX82携带的87K PAI的转移频率8.46×10^(−6)。与受体菌P1/7RIF相比,两个89K样PAIs的接合子P1/7RIF-GX54与P1/7RIF-GX82的四环素类和大环内酯类抗生素的抗性水平,以及对斑马鱼的致病力均显著增加,且两接合子组间的致病力差异无统计学意义(P>0.05)。菌株GX54和菌株GX82感染C57BL/6小鼠后,菌株GX54感染组小鼠死亡率显著高于菌株GX82感染组(P<0.05)。攻毒8 Objective To investigate the genomic and biological characteristics of 89K-like pathogenicity islands(PAIs),and their roles in the pathogenesis of Streptococcus suis.Methods Bioinformatics methods were used to analyze the genomic characteristics of the 89K-like PAIs.The transferability frequencies of the 89K-like PAIs were evaluated in conjugation assay.The antibiotic susceptibility profiles of the clinical strains and corresponding transconjugants were investigated by the minimum inhibitory concentration test.The pathogenicity of the clinical strains and corresponding transconjugants was evaluated using C57BL/6 mouse infection model and zebrafish infection model,respectively.Results The sequence type(ST)of S.suis clinical strains GX54 and GX82 harboring 89K-like PAIs was ST665 and ST107,respectively.GX54 harbored a 75Kb PAI that exhibited 99.21%identity and 79.00%coverage to the 89K PAI carried by the ST7 epidemic strain SC84.In contrast,GX82 harbored an 87Kb PAI that exhibited 98.80%identity and 86.00%coverage to the 89K PAI.Both PAIs were integrated into the rplL site and contained a 15-bp att sequence 5′-TTATTTAAGAGTAAC-3′in the flanking regions.Furthermore,both PAIs possessed a complete modular structure,including a functional NisK-NisR-like two-component signal transduction system and a type IV secretion system(T4SS).However,the SalK gene of the SalR-SalK-like two-component signal transduction system was truncated.The 75Kb PAI contained four additional genes,including two hypothetical protein genes,tet(O),and erm(B).On the other hand,the 87Kb PAI harbored 12 additional genes,ontaining plasmid-related recombinases genes,truncated replication protein genes,cat,tet(L),and erm(B).Additionally,genes encoding transposases and topoisomerases were also present.The transferability frequency of the 89K-like PAI harbored in strain GX54 was 4.61×10^(−5),significantly higher than the 8.46×10^(−6) of the 89K-like PAI harbored in strain GX82(P<0.05).The 89K-like PAIs conferred the tetracycline and macrolide resi

关 键 词：猪链球菌 89K样毒力岛 接合 耐药性 致病 

分 类 号：R211[医药卫生—中医学] R378.1