N-乙酰转移酶对罗非鱼无乳链球菌毒力相关特性的影响  

Effect of N-acetyltransferase on virulence properties of Streptococcus agalactiae

作　　者：马天雨 石富强 刘欣 张永安 曾辉 MA Tianyu;SHI Fuqiang;LIU Xin;ZHANG Yongan;ZENG Hui(College of Fisheries,Huazhong Agricultural University/Hubei Hongshan Laboratory,Wuhan 430070,China;Guangdong Laboratory for Lingnan Modern Agriculture,Guangzhou 510642,China)

机构地区：[1]华中农业大学水产学院/湖北洪山实验室,武汉430070 [2]岭南现代农业科学与技术广东省实验室,广州510642

出　　处：《华中农业大学学报》2024年第6期289-296,共8页Journal of Huazhong Agricultural University

基　　金：武汉市知识创新专项-基础研究项目(2023020201010103);中央高校基本科研业务费专项(2662023PY021);国家现代农业产业技术体系专项(CARS-46);国家自然科学基金面上项目(32173015);岭南现代农业实验室科研项目(NT2021008)。

摘　　要：为阐明N-乙酰转移酶(NAT)在无乳链球菌致病过程中的作用,利用同源重组法构建野生株HN016的nat基因缺失株Δnat,并比较野生株和缺失株的生长、形态、黏附入侵细胞能力、抗吞噬能力、全血存活能力和致病力。结果显示,Δnat的溶血能力降低,并且nat缺失导致无乳链球菌对罗非鱼脑细胞的黏附和入侵能力下降,并增加了细菌对血液杀伤和吞噬细胞吞噬的敏感性。罗非鱼感染试验结果显示,nat基因缺失株Δnat(2×10^(8) CFU/尾,致死率为36%)对罗非鱼的致死力显著低于野生株HN016(2×10^(8) CFU/尾,致死率为85%)。罗非鱼感染12 h后,与野生对照株相比,Δnat突变株在血液、脾脏和脑组织中载菌量显著降低。研究表明,N-乙酰转移酶参与无乳链球菌抵抗宿主血液和吞噬细胞的清除,并协助细菌对罗非鱼组织的入侵和定植。To explore the effect of N-acetyltransferase(NAT)on the pathogenicity of Streptococcus agalacae,the nat gene deletion strainΔnat was constructed by homologous recombination in the background of a wild strain HN016.The growth curve,morphology,cell adhesion,invasion,antiphagocytosis,whole blood survival and pathogenicity of wild strain andΔnat strain were compared.The results showed that the hemolytic capacity ofΔnat decreased,and the loss of nat decreased the adhesion and invasion of S.agalactiae to tilapia brain cells and increased the bacterial susceptibility to blood killing and phagocytosis.The result of challenge experiment of tilapia showed that the lethality ofΔnat(2×10^(8) CFU/fish,the mortality rate was 36%)was significantly lower than that of wild strain HN016(2×10^(8) CFU/fish,the mortality rate was 85%).And the bacterial loads ofΔnat were much less than that of HN016 in blood,spleen and brain tissue at 12 h post infection.This study firstly reports that NAT plays an important role in S.agalactiae resistance to host blood and phagocyte clearance,and assists in the bacterial invasion and colonization of tilapia tissues.

关 键 词：无乳链球菌 N-乙酰转移酶 基因缺失 生物学特性 罗非鱼 

分 类 号：S917.1[农业科学—水产科学]