流产布鲁菌ppdk基因缺失株的构建及其生物学特性分析

CONSTRUCTION AND BIOLOGICAL CHARACTERIZATION OF A PPDK MUTANT OF BRUCELLA ABORTUS

布鲁菌病是由布鲁菌感染引起的呈全球性分布的人畜共患细菌性传染病。布鲁菌是一种兼性胞内菌,感染宿主依赖多种基因的表达和调控。近年来,胞内菌的碳代谢与致病力的关系成为研究的热点。前期研究发现碳代谢相关的丙酮酸磷酸双激酶(ppdk)基因与布鲁菌毒力相关。本研究利用同源重组方法构建流产布鲁菌ppdk基因缺失株,通过环境压力因子耐受性实验、胞内存活实验和动物致病性实验等探讨ppdk基因对布鲁菌毒力的影响。结果显示,ppdk基因缺失能减弱布鲁菌对多粘菌素B和大牛血清的抵抗性,减弱细菌胞内存活的能力和对小鼠的致病力,表明ppdk基因与流产布鲁菌的毒力密切相关。

Brucellosis caused by Brucella spp. has been one of the most prevalent bacterial zoonosis worldwide. The etiological agent is a facultative intraeellular bacterium, and infects hosts depending on the expression and regulation of virulence genes. Recently, one research hotpot is about links between carbon metabolism and virulence for intracellular bacteria. In our previous study, we found that a metabolism related pyruvate phosphate dikinase （ppdk） encoded by ppdk gene was associated with Brucella virulence. In this study, we constructed appdk mutant via homologous recombination method. In order to study the function ofppdk gene on Bmcella virulence, we tested its resistance to environmental stress factors, survival within RAW264.7 cells and pathogenecity to BALB/c mice. As compared with the wild-type parent strain $2308, theppdk mutant was more sensitive to polymyxin B and natural bovine serum, decreased survival ability within RAW264.7, and attenuated virulence in mice, suggesting thatppdk gene plays a crucial role on the Brucella virulence.