猪链球菌2型Ⅲ型溶血素的研究

为了探讨猪链球菌2型(Streptococcus suis serotype 2,SS2)的Ⅲ型溶血素是否具有溶血活性以及Ⅲ型溶血素在SS2致病过程中的作用,本研究利用同源重组基因敲除法成功构建了SS205ZY的Ⅲ型溶血素(slyrp)基因缺失突变菌株△slyrp及双基因缺失突变菌株△sly/△slyrp,并比较了野生菌株和基因缺失突变菌株的溶血能力以及对小鼠的致病力.结果表明,slyrp基因敲除后可导致SS2裂解红细胞的能力有所下降,而双基因缺失突变菌株△sly/△slyrp的溶血能力完全丧失；slyrp基因敲除后对小鼠的致病力没有影响.结果提示猪链球菌2型Ⅲ型溶血素具有一定的溶血能力,该Ⅲ型溶血素在SS2感染过程中,对溶血素(sly)起协同作用,不是SS2主要的毒力相关基因.

STUDIES ON HEMOLYSIN TYPE III OF STREPTOCOCCUS SUIS SEROTYPE 2

It has been believed that an ORF encoding a putative hemolytic type III exists in many virulent Streptococcus suis serotype 2 and 9 strains.However,there is no experimental evidence for expression of any other active hemolysins except suilysin.This experiment was conducted to find out whether hemolytic type III of Streptococcus suis serotype 2(SS2) had hemolytic capability and played a role in pathogenecity.Two mutants,SS205ZY isogenic hemolytic type III mutant(△slyrp) and two gene knock out mutant Δsly/slyrp,were constructed through homologous recombination and compared their hemolytic capability and virulence to mice with the wild type strain.The SS205ZY mutant showed decreased hemolytic capability while Δsly/slyrp mutant lost hemolytic capability.Knocking out the slyrp gene did not affect the virulence to mice.The results showed that hemolytic type III of SS2 had some hemolytic capability,which had synergistic effect with suilysin.Therefore,the hemolytic type III was not the important virulence-associated factor of SS2.