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Published on: February 23, 2014
Cell surface proteins in S. pneumoniae, S. mitis and S. oralis
A Madhour1, P Maurer, R Hakenbeck
1Department of Microbiology, University of Kaiserslautern, Paul-Ehrlich Str. 23, D-67663 Kaiserslautern.
Background And Objectives:
Streptococcus pneumoniae, a major human pathogen, is closely related to the commensal species S. mitis and S. oralis. S. pneumoniae surface proteins are implicated in virulence and host interaction of this species, but many of them have recently been detected in S. mitis B6 in silico. We tested for the presence of such genes usinga set of eight S. mitis and eleven S. oralis strains from different geographic locations.
Materials And Methods:
An oligonucleotide microarray was designed based on the genomes of S. pneumoniae R6 and TIGR4 as well as S. mitis B6 to include 63 cell surface proteins. The S. pneumoniae genes encoding neuraminidases, hyaluronidase and pneumolysin were also included. In addition to comparative genomic hybridization experiments, homologues were identified in silico in the genome of S. oralis Uo5.
Results And Conclusions:
The results document that many S. pneumoniae related surface proteins are ubiquitously present among the Mitis group of streptococci. All 19 samples hybridized with the pavA probe representing a gene important for adherence and invasion of S. pneumoniae. Only eight genes were not recognized in any strain, including the S. pneumoniae PcpC gene as the only virulence gene of the S. pneumoniae core genome.The fact that only 12 out of 26 genes present in the S. oralis Uo5 genome could be detected by microarray analysis confirms the sequence variation of surface components.
Insights
Many Streptococcus pneumoniae surface protein genes are found in related commensal bacteria, Streptococcus mitis and Streptococcus oralis. This suggests these genes may play roles beyond S. pneumoniae virulence.
Area of Science:
- Microbiology
- Genomics
- Bacterial Pathogenesis
Background:
- Streptococcus pneumoniae is a significant human pathogen closely related to commensal species S. mitis and S. oralis.
- Surface proteins of S. pneumoniae are crucial for virulence and host interactions.
- Previous in silico analysis revealed S. pneumoniae surface proteins in S. mitis B6.
Purpose of the Study:
- To investigate the presence of S. pneumoniae-associated surface protein genes in commensal S. mitis and S. oralis strains.
- To understand the distribution and potential roles of these genes in related streptococcal species.
Main Methods:
- Oligonucleotide microarray design based on S. pneumoniae and S. mitis genomes, including 63 cell surface proteins and key virulence genes.
- Comparative genomic hybridization experiments on 8 S. mitis and 11 S. oralis strains.
- In silico identification of homologous genes in the S. oralis Uo5 genome.
Main Results:
- Many S. pneumoniae-related surface protein genes are ubiquitously present in the Mitis group streptococci.
- The pavA gene, important for adherence and invasion, was detected in all 19 strains.
- Only eight genes, including the S. pneumoniae PcpC virulence gene, were not found in any strain.
Conclusions:
- The study confirms the widespread presence of S. pneumoniae-like surface proteins in commensal Mitis group streptococci.
- Sequence variation in surface components is significant, as evidenced by incomplete detection of S. oralis genes via microarray.
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