猪链球菌2型菌毛骨架蛋白编码基因SSU2101敲除突变株的构建及其生物学功能

利用同源重组基因敲除方法构建猪链球菌2型(Streptococcus suis serotype2,S.suis2)中国强毒株05ZYH33菌毛骨架蛋白(Backbone protein,BP)编码基因SSU2101敲除突变株。采用引物特异性PCR分析、Southern杂交及RT-PCR等方法鉴定,证实成功构建了BP基因缺失突变株。生物学特性显示,突变株的菌落形态、溶血活性以及染色特性方面与野生株之间均无明显差异。小鼠致病性试验结果显示,突变株的毒力比野生株显著减弱。研究结果提示菌毛在S.suis2感染致病过程中起重要作用,为系统研究S.suis2菌毛分子装配机制及其生物学功能奠定了基础。

Construction and Characterization of Pilus Backbone Gene Knock-out Mutant of Streptococcus suis Serotype 2

Based on the principle of homologous recombination, we construct gene knock-out mutant of the pilus backbone gene in Streptococcus suis serotype 2 virulent strain 05ZYH33. PCR analysis, Southern hybridization and RT-PCR analysis showed that the target gene was replaced by SpcR cassette. Analysis of biological characteristics showed that there were no differences in mycelial morphology, hemolytic activity and dyeing properties between the mutant and the wild type strain 05ZYH33. Virulence assays with murine model confirmed that the mutant is significantly less virulent than the wild type strain. The results suggest pili plays an important role in the pathogenesis, which laid the foundation for the study of the mechanisms of pilus assembly and biological function in the S. suis serotype 2.