肺炎链球菌的转化缺陷导致细菌毒力减弱

的探讨肺炎链球菌的自然转化与其条件致病的关系。方法采用插入失活的方法制备肺炎链球菌的转化缺陷菌株，通过黏附实验和小鼠毒力实验观察它们毒力的变化，应用RT-PCR测定黏附因子PsaA在野生和缺陷菌株中的表达。结果实验获得了3株肺炎链球菌(1、2和22)的转化缺陷菌株(1d、2d和22d)。毒力研究发现转化缺陷菌株对ECV 304细胞的黏附能力显著弱于相应的野生菌株，1和2株肺炎链球菌腹腔感染BALB／c小鼠的能力显著强于相应的转化缺陷菌株；研究还发现PsaA基因在2和22株肺炎链球菌中的表达量显著高于其缺陷菌株。结论肺炎链球菌具有自然转化的能力有助于其毒力的表现，且可能通过黏附因子PsaA等相关毒力因子表达增加而增强其毒力。

The effect of transformation on virulence of Streptococcus pneumoniae

Objective The effect of pneumococcal transformation on its pathogenesis was investigated. Methods Three transformation-deficient strains No.1d, 2d and 22d were established by the insertion of inactivating gene comE. The virulence of transformation-deficient strains were compared with the wild ones by challenging mice through intraperitoneal route, by adhering to ECV 304 cells in vitro and by detecting their gene PsaA mRNA expression. Results In comparison with the wild strains, the adherence rates of all transformation-deficient strains to ECV 304 cell were significantly reduced(P<0.05), the median survival time of No.1d and 2d strains significantly increased by challenging mice through intraperitoneal route (P<0.05), and the mRNA expressions of PsaA were reduced (P<0.05) in No.2d and 22d strains. Conclusion These results indicated that transformation might affect the virulence expression in S.pneumoniae.