丝氨酸/苏氨酸激酶对猪链球菌2型应激和毒力的影响

The impact of serine/threonine kinase on stress response and virulence of Streptococcus suis type 2

为阐明丝氨酸/苏氨酸激酶(STK)对猪链球菌2型强毒株的应激耐受和毒力的影响,比较了亲本株SS2-1及其丝氨酸/苏氨酸激酶基因缺失株Δstk在各种应激环境(热、酸、氧化应激和高渗应激)中的生长能力,利用HEp-2细胞模型比较各菌株的黏附能力,比较各菌株在猪全血中的存活能力,利用仔猪模型评价STK基因缺失前后细菌的毒力差异。结果表明,丝氨酸/苏氨酸激酶基因缺失后,细菌在各种应激环境中的生存能力明显减弱,对HEp-2细胞的黏附能力减弱,在猪全血中的存活能力显著降低,对仔猪的致病力明显降低。此外,缺失株Δstk在仔猪体内各器官的定殖能力也显著降低。说明丝氨酸/苏氨酸激酶与猪链球菌的应激和毒力密切相关。

To investigate the effect of serine/threonine kinases（ STK） in Streptococcus suis type 2 virulent strain on stress tolerance and virulence,the growth characteristics of wild type SS2-1 and STK-deletion strain Δstk were compared under different stress conditions（ high temperature,acidic p H,oxidative stress,and high osmolarity.） in vitro. The Δstk mutant showed defects in their ability to grow under various stress conditions,compared to the wild-type strain. The Δstk exhibited a significant decrease in HEp-2 cell adhesion,and a reduced survival rate in whole blood. In the piglet model,the Δstk also showed a weak virulence compared to wild-type strain. The in vivo colonization experiments revealed that the mutant strain Δstk displayed reduced bacterial colonization in the tissues of piglets. These results suggest that the STK is closely related to the stress response and virulence of SS2.