为鉴定猪链球菌2型强毒株SS2-1调控因子Rex基因的缺失对细菌毒力的影响,本研究利用同源重组方法构建猪链球菌Rex缺失株,命名为SS2-1△Rex,并通过缺失株的生物学特性及其小鼠致病性试验进行鉴定.结果显示亲本株、缺失株及互补株在溶血能力、增殖特性和革兰染色形态无显著差异;在对小鼠致病性试验中,接种SS2-1组小鼠死亡率为87.5％,而SS2-1△Rex组死亡率为12.5％,SS2-1△Re√pRex对小鼠的毒力有所恢复,死亡率为50％;Log-Rank (Mantel-Cox)对数秩检验分析结果显示亲本株和缺失株对小鼠致病性存在显著差异.本研究结果表明调节因子Rex是猪链球菌2型的毒力相关因子.本实验为深入研究Rex调控毒力因子的转录和表达及其具体的机制奠定了实验基础.%To investigate the role of the Redox regulator (Rex) in the pathogenicity of Streptococcus suis type 2 (SS2) virulent strain SS2-1,the Rex gene was knocked out from the chromosome of SS2-1 strain using homologous recombination system,and the mutant was named SS2-1△Rex,which was identified by its biological properties and virulence on a murine model.The results confirmed that the isogenic Rex mutant strain SS21-△Rex and complemented strain SS2-1△Rex/pRex were successfully constructed.No significant differences were observed among the SS2-1,SS2-1△Rex and SS2-1△Rex/pRex strains in biological characteristics,including growth rate,colony morphology and hemolytic activity.Compared with the wild type strain SS2-1,the virulence of the SS2-1△Rex was attenuated to BALB/c mice.In conclusion,The transcriptional regulator Rex was closely related to the virulence of SS2.
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