title: The contribution of suilysin to the pathogenesis of Streptococcus suis meningitis.
abstract: BACKGROUND
  Streptococcus suis is an emerging zoonotic pathogen, and causes sepsis and meningitis in humans. Although sequence type (ST) 1 and ST104 strains are capable of causing sepsis, ST1 strains commonly cause meningitis. In this study, we investigated the role of suilysin, a member of cholesterol-dependent cytolysins, in differential pathogenicity between ST1 and ST104 strains.
  
  
  METHODS
  The levels of transcription and translation of the sly gene and messenger RNA of both ST strains were compared by means of quantitative polymerase chain reaction and Western blotting. Survival rates and bacterial densities in brain were compared between mice infected with wild-type and sly-knockout ST1 strain. ST104 infections with or without complementation of suilysin were also assessed.
  
  
  RESULTS
  The amounts of suilysin produced by ST1 strains were much higher than those produced by ST104 strains. Lower production of suilysin by ST104 strains were attributed to the attenuated sly gene expression, which seemed to be associated with 2 nucleotide insertions in sly promoter region. Furthermore, suilysin contributed to the higher bacterial density and enhanced inflammation in brain and increased mortality.
  
  
  CONCLUSIONS
  Our data may explain why ST1 strains, but not ST104 strains, commonly cause meningitis and also suggest the contribution of suilysin to the pathogenesis of meningitis in humans.
authors.affiliation: Laboratory for Clinical Research on Infectious Diseases, International Research Center for Infectious Diseases, Research Institute for Microbial Diseases, Osaka University.
authors.forename: Dan
authors.initials: D
authors.lastname: Takeuchi
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Akeda
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Nakayama
authors.forename: Anusak
authors.initials: A
authors.lastname: Kerdsin
authors.forename: Yasuteru
authors.initials: Y
authors.lastname: Sano
authors.forename: Takashi
authors.initials: T
authors.lastname: Kanda
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Hamada
authors.forename: Surang
authors.initials: S
authors.lastname: Dejsirilert
authors.forename: Kazunori
authors.initials: K
authors.lastname: Oishi
mesh_terms: D000818:Animals; D001422:Bacterial Adhesion; D002460:Cell Line; D042783:Endothelial Cells / Q000382:microbiology; D005260:Female; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D006460:Hemolysin Proteins / Q000378:metabolism*; D006801:Humans; D016920:Meningitis, Bacterial / Q000378:metabolism*; D051379:Mice; D012333:RNA, Messenger; D011817:Rabbits; D044967:Serum / Q000276:immunology; D013290:Streptococcal Infections / Q000382:microbiology*; D017011:Streptococcus suis / Q000145:classification / Q000378:metabolism* / Q000472:pathogenicity; D014158:Transcription, Genetic; D014774:Virulence; D015047:Zoonoses
chemical_list: D006460:Hemolysin Proteins; D012333:RNA, Messenger; C104760:suilysin
keywords: ST104; Streptococcus suis; meningitis; sequence type (ST) 1; suilysin