title: Increased production of suilysin contributes to invasive infection of the Streptococcus suis strain 05ZYH33.
abstract: Streptococcus suis serotype 2 (SS2) is widely recognized in the veterinary world as the cause of rapidly progressive and fatal sepsis in infant pigs, manifested with meningitis, polyarthritis and pneumonia. It has evolved into a highly infectious strain, and caused two large-scale outbreaks of human epidemic in China, characterized bytypical toxic-shock syndrome and invasive infection. However, the molecular basis of virulence of this emerging zoonotic pathogen is still largely unknown. The present study shows that the sequence type (ST)7 epidemic strain S. suis 05ZYH33 causes higher mortality, higher necrosis of polymorphonuclear neutrophils and a significantly higher damage to human umbilical vein endothelial cells compared to the non-epidemic strain S. suis 1940. These differences appear to associate with the enhanced secretion of suilysin (sly) by S. suis 05ZYH33 compared to the non-epidemic strain 1940. Inclusion of additional strains confirmed that the epidemic ST7 strains produce more sly protein (mean, 1.49 g/ml; range, 0.76‑1.91 g/ml) than non‑epidemic strains (mean, 0.33 g/ml; range, 0.07-0.94 g/ml), and this difference is significant (P<0.001). The nonpolar mutant strain S. suis Δsly, constructed from the epidemic ST7 strain S. suis 05ZYH33 confirmed the role of sly on the enhanced virulence of S. suis ST7 strains. These findings suggest that increased sly production in S. suis 05ZYH33 facilitates penetration to the epithelium and its survival in the bloodstream, thereby contributing to the invasive infection.
authors.affiliation: Department of Clinical Laboratory, Bethune International Peace Hospital of PLA, Shijiazhuang, Hebei 050082, P.R. China.
authors.forename: Zhengxin
authors.initials: Z
authors.lastname: He
authors.affiliation: State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Academy of Military Medical Sciences, Beijing 100071, P.R. China.
authors.forename: Yaya
authors.initials: Y
authors.lastname: Pian
authors.affiliation: State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Academy of Military Medical Sciences, Beijing 100071, P.R. China.
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Ren
authors.affiliation: State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Academy of Military Medical Sciences, Beijing 100071, P.R. China.
authors.forename: Lili
authors.initials: L
authors.lastname: Bi
authors.affiliation: State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Academy of Military Medical Sciences, Beijing 100071, P.R. China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Yuan
authors.affiliation: State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Academy of Military Medical Sciences, Beijing 100071, P.R. China.
authors.forename: Yuling
authors.initials: Y
authors.lastname: Zheng
authors.affiliation: State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Academy of Military Medical Sciences, Beijing 100071, P.R. China.
authors.forename: Yongqiang
authors.initials: Y
authors.lastname: Jiang
authors.affiliation: Department of Clinical Laboratory, Bethune International Peace Hospital of PLA, Shijiazhuang, Hebei 050082, P.R. China.
authors.forename: Fukun
authors.initials: F
authors.lastname: Wang
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004848:Epithelium / Q000378:metabolism / Q000473:pathology / Q000821:virology; D005260:Female; D006460:Hemolysin Proteins / Q000378:metabolism*; D061307:Human Umbilical Vein Endothelial Cells / Q000378:metabolism / Q000473:pathology / Q000821:virology; D006801:Humans; D051379:Mice; D013290:Streptococcal Infections / Q000378:metabolism* / Q000473:pathology* / Q000821:virology; D017011:Streptococcus suis
chemical_list: D006460:Hemolysin Proteins; C104760:suilysin