title: Roles of virulence genes (PsaA and CpsA) on the invasion of Streptococcus pneumoniae into blood system.
abstract: BACKGROUND
  Streptococcus pneumoniae (SP) is the major cause of childhood mortality worldwide, we need to understand virulence genes of SP so can better target the treatment.We investigated the expression of virulence genes PsaA and CpsA in different strains of SP interacting with monocyte cell line (THP-1) or pneumocyte cell line (A549) and the possible mechanism of SP invasion of the blood system.
  
  
  METHODS
  A total of 23 strains of SP were collected from hospitalized patients (blood-derived and sputum-derived) in the Second Affiliated Hospital of Wenzhou Medical College. The strains and ATCC 49619 were cultured, and RNAs were extracted. THP-1 and A549 cells were stimulated by different SP and ATCC 49619 for 4 h and 8 h, respectively. Quantitative real-time PCR was used to analyze the mRNA expression of PsaA and CpsA. The data were analyzed by SPSS 17.0.
  
  
  RESULTS
  The mRNA level of PsaA and CpsA were all significantly increased in clinical SP strains when compared to ATCC49619 after tedTHP-1 and A549 cells were stimulated. Clinical SPs showed higher virulence compared with ATCC49619.
  
  
  CONCLUSIONS
  The expression of CpsA is the basis of the pathogenicity of SP. The expression of virulence gene PsaA may be helpful to the invasion of SP to the blood system.
authors.affiliation: Department of Laboratory Medicine, Taizhou Municipal Hospital, 381 Zhongshan East Road, Jiaojiang District, Taizhou City, Zhejiang Province 318000, China.
authors.forename: Da-kang
authors.initials: DK
authors.lastname: Hu
authors.forename: Dong-guo
authors.initials: DG
authors.lastname: Wang
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.forename: Chi-bo
authors.initials: CB
authors.lastname: Liu
authors.forename: Lian-hua
authors.initials: LH
authors.lastname: Yu
authors.forename: Ying
authors.initials: Y
authors.lastname: Qu
authors.forename: Xin-hua
authors.initials: XH
authors.lastname: Luo
authors.forename: Jin-hong
authors.initials: JH
authors.lastname: Yang
authors.forename: Jian
authors.initials: J
authors.lastname: Yu
authors.forename: Jin
authors.initials: J
authors.lastname: Zhang
authors.forename: Xiang-yang
authors.initials: XY
authors.lastname: Li
mesh_terms: D018829:Adhesins, Bacterial / Q000235:genetics*; D056809:Alveolar Epithelial Cells / Q000166:cytology / Q000378:metabolism / Q000473:pathology; D001426:Bacterial Proteins / Q000235:genetics*; D001769:Blood / Q000382:microbiology; D002460:Cell Line; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D008074:Lipoproteins / Q000235:genetics*; D009000:Monocytes / Q000166:cytology / Q000378:metabolism / Q000473:pathology; D011018:Pneumonia, Pneumococcal / Q000097:blood / Q000235:genetics* / Q000382:microbiology / Q000473:pathology*; D013183:Sputum / Q000382:microbiology; D013296:Streptococcus pneumoniae / Q000235:genetics / Q000472:pathogenicity*
chemical_list: D018829:Adhesins, Bacterial; D001426:Bacterial Proteins; C500439:CpsA protein, Streptococcus pneumoniae; D008074:Lipoproteins; C085000:PsaA protein, Streptococcus