Streptococcus suis 05ZY: wt vs SSU05_0930 knockout strain. Streptococcus suis 05ZY: wt vs SSU05_0930 knockout strain

Two large-scale outbreaks of streptococcal toxic shock-like syndrome (STSLS) have revealed Streptococcus suis 2 (SS2) to be a severe, evolving pathogen in humans. We investigated the mechanism by which SS2 causes STSLS. The transcriptional regulator TstS up-regulated during experimental infection. Compared with the wild type 05ZY strain, the tstS deletion mutant (∆tstS) elicited reduced cytokine secretion in macrophages. In mice, tstS deletion decreased virulence, bacterial load, and cytokine production. Moreover, TstS expression in P1/7 strain led to induction of STSLS in the infected mice. This is noteworthy because although virulent, P1/7 does not normally induce STSLS. Through microarray-based comparative transcriptomics analysis, we found that TstS regulates multiple metabolism related genes and several virulence-related genes associated with immune evasion. Overall design: Streptococcus suis 05ZY (wt) and its SSU05_0930 knockout strain were harvested at the logarithmic phase of growth. Four independent experiments were performed at each time