前噬菌体lamdaSa04对鱼源无乳链球菌环境适应性及致病性的影响  

Effects of prophage lamdaSa04 on environmental fitness and pathogenicity of piscine Streptococcus agalactice

作　　者：姬姝婷 曹青[1] 聂蒙 董雨豪 刘广锦[1] 刘永杰[1] JI Shuting;CAO Qing;NIE Meng;DONG Yuhao;LIU Guangjin;LIU Yongjie(College of Veterinary Medicine,Nanjing Agricultural University,Nanjing 210095,China)

机构地区：[1]南京农业大学动物医学院,江苏南京210095

出　　处：《南京农业大学学报》2022年第6期1194-1202,共9页Journal of Nanjing Agricultural University

基　　金：江苏省自然科学基金项目(BK20171376);江苏高校优势学科建设工程项目(PAPD)。

摘　　要：[目的]本文旨在调查前噬菌体lamdaSa04对鱼源无乳链球菌GD201008-001环境适应性和毒力的影响。[方法]利用同源重组技术构建前噬菌体lamdaSa04基因缺失株,比较缺失株与野生株在体外生长、抗环境应激、抗巨噬细胞吞噬、胞内存活以及感染小鼠的存活率和组织细菌载量等方面的差异。[结果]lamdaSa04基因簇缺失不影响无乳链球菌GD201008-001的体外生长能力,但生物被膜形成能力下调38.57%;在10和20 mmol·L^(-1)H_(2)O_(2)的强氧化应激条件下,缺失株存活率较野生株分别下调22.86%及42.01%;小鼠巨噬细胞RAW264.7对缺失株的吞噬率比野生株上调76.12%。模拟巨噬细胞的内环境,在强氧化、一氧化氮、溶菌酶、强酸等多因素结合的应激条件下,检测菌株的存活率,结果表明lamdaSa04的存在有助于无乳链球菌在氧化应激和酸应激条件下的存活。动物试验结果显示,缺失lamdaSa04基因对小鼠致死率及组织细菌载量无明显影响。[结论]前噬菌体lamdaSa04的存在对无乳链球菌的环境适应性有显著影响,但并不影响细菌的致病性。[Objectives]The aim of this study was to investigate the effects of prophage lamdaSa04 on pathogenicity and environmental fitness of piscine Streptococcus agalactice GD201008-001.[Methods]Homologous recombination technology was used to construct the deletion strain of lamdaSa04 gene.The differences in biological characteristics were compared between the deletion strain and the wild strain,including the abilities of growth in vitro,anti-environmental stress,anti-phagocytosis against macrophages,intracellular survival,and survival rate and tissue bacterial load of infected mice.[Results]The deletion of lamdaSa04 gene cluster did not affect the growth ability of S.agalactiae GD201008-001 in vitro,but the biofilm formation ability was downregulated by 38.57%.Under the condition of strong oxidative stress with 10 and 20 mmol·L^(-1)H_(2)O_(2),the survival rates of the deletion strain were 22.86%and 42.01%,respectively,lower than those of the wild strain.The phagocytosis rate of mouse macrophage RAW264.7 to the deletion strain was 76.12%,higher than that to the wild strain.To simulate the environment in macrophages,the stress conditions of strong oxidation,nitric oxide,lysozyme and strong acid were set,and then the bacterial survival rates were detected.The data showed that the lamdaSa04 was conducive to the survival of S.agalactiae under strong acid and oxidation conditions.The results of animal experiments showed that the deletion of lamdaSa04 had no significant effect on the mortality and tissue bacterial load in mice.[Conclusions]The prophage lamdaSa04 has a significant effect on the environmental adaptability of S.agalactiae,but doesn’t affect the pathogenicity of this bacterium.

关 键 词：无乳链球菌 前噬菌体 lamdaSa04 环境适应性 致病性 

分 类 号：S852.61[农业科学—基础兽医学]