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. 2013 May 17;18(1):14.
doi: 10.1186/2047-783X-18-14.

Roles of virulence genes (PsaA and CpsA) on the invasion of Streptococcus pneumoniae into blood system

Da-kang Hu  1 , Dong-guo Wang, Yang Liu, Chi-bo Liu, Lian-hua Yu, Ying Qu, Xin-hua Luo, Jin-hong Yang, Jian Yu, Jin Zhang, Xiang-yang Li
Affiliations

Roles of virulence genes (PsaA and CpsA) on the invasion of Streptococcus pneumoniae into blood system

Da-kang Hu et al. Eur J Med Res. .

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.

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Figures

Figure 1
Figure 1
Morphological changes of THP-1 and A549 cells after Streptococcus pneumoniae (SP) infection. THP-1 and A549 cells began to die after infection at 4 to 8 hours: A) THP-1 at 0 hours; B) THP-1 at 4 hours; C) THP-1 at 8 hours; D) A549 at 0 hours; E) A549 at 4 hours; F), A549 at 8 hours. (×200).
Figure 2
Figure 2
The expression of PsaA gene in THP-1 (A) and A549 (B) cells at 0 hours, 4 hours, and 8 hours.
Figure 3
Figure 3
The expression of CpsA gene in THP-1 (A) and A549 (B) cells at 0 hours, 4 hours, and 8 hours.
See this image and copyright information in PMC

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