Unknown,Transcriptomics,Genomics,Proteomics

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Activity of SigB Modulates Virulence Gene Expression in a Murine Staphylococcus aureus Infection Model but Does Not Influence the Host Kidney Gene Expression

ABSTRACT: Background. Infections caused by Staphylococcus aureus are associated with significant morbidity and mortality and are an increasing threat not only in hospital settings. The expression of the staphylococcal virulence factor repertoire is known to be affected by the alternative sigma factor B (SigB). However, its impact during infection still is a matter of debate. Methods. Kidney tissue of controls or mice infected with S. aureus HG001 or its isogenic sigB mutant was analyzed by transcriptome profiling to monitor the host response, and additionally expression of selected S. aureus genes was monitored by RT-qPCR. Results. Direct transcript analysis by RT-qPCR revealed significant SigB activity in all mice infected with the wild type strain (WT), but not in its isogenic sigB mutant (p<0.0001). Despite a clear cut difference in the SigB-dependent transcription pattern of virulence genes (clfA, aur, and hla), the host reaction to infection (either WT or sigB mutant) was almost identical. Conclusions. Despite its significant activity in vivo, loss of SigB did not have an effect on the outcome of infection as well as on murine kidney gene expression pattern. Thus, these data support the role of SigB as virulence modulator rather than being a virulence determinant by itself. Murine kidney gene expression pattern of 3 groups were compared: 1) after infection with S. aureus HG001 (wild type); 2) after infection with S. aureus HG001 ΔsigB; 3) sham control (injection of physiological saline solution). The infection was performed twice (2 biological replicates), and the array analysis included 4 or 5 mice (independent samples) per group. In total, the study consisted of 24 arrays.

ORGANISM(S): Mus musculus

SUBMITTER: Maren Depke

PROVIDER: E-GEOD-28540 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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The alternative sigma factor B modulates virulence gene expression in a murine Staphylococcus aureus infection model but does not influence kidney gene expression pattern of the host.

Depke Maren M Burian Marc M Schäfer Tina T Bröker Barbara M BM Ohlsen Knut K Völker Uwe U

International journal of medical microbiology : IJMM 20111022 1

Infections caused by Staphylococcus aureus are associated with significant morbidity and mortality and are an increasing threat not only in hospital settings. The expression of the staphylococcal virulence factor repertoire is known to be affected by the alternative sigma factor B (SigB). However, its impact during infection still is a matter of debate. Kidney tissues of controls or mice infected with S. aureus HG001 or its isogenic sigB mutant were analyzed by transcriptome profiling to monitor ...[more]

PMID: 22019488

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Project description:Staphylococcus aureus is a human pathogen that can cause a wide range of diseases. Although formerly regarded as extracellular pathogen, it has been shown that S. aureus can also be internalized by host cells and persist within these cells. In the present study, we comparatively analyzed survival and physiological adaptation of S. aureus HG001 after internalization by two human lung epithelial cell lines (S9 and A549), and human embryonic kidney cells (HEK 293). Combining enrichment of bacteria from host-pathogen assays by cell sorting and quantitation of the pathogen's proteome by mass spectrometry we characterized S. aureus adaptation during the initial phase between 2.5 h and 6.5 h post-infection. Starting with about 2 × 10^6 bacteria, roughly 1450 S. aureus proteins, including virulence factors and metabolic enzymes were identified by spectral comparison and classical database searches. Most of the bacterial adaptation reactions, such as decreased levels of ribosomal proteins and metabolic enzymes or increased amounts of proteins involved in arginine and lysine biosynthesis, enzymes coding for terminal oxidases and stress responsive proteins or activation of the sigma factor SigB were observed after internalization into any of the three cell lines studied. However, differences were noted in central carbon metabolism including regulation of fermentation and threonine degradation. Since these differences coincided with different intracellular growth behavior, complementary profiling of the metabolome of the different non-infected host cell types was performed. This revealed similar levels of intracellular glucose but host cell specific differences in the amounts of amino acids such as glycine, threonine or glutamate. With this comparative study we provide an impression of the common and specific features of the adaptation of S. aureus HG001 to specific host cell environments as a starting point for follow-up studies with different strain isolates and regulatory mutants. Metabolome analysis, by nuclear magnetic resonance spectroscopy, was performed for the infection medium (extracellular medium, mock infection of 1 h).

Dataset Information

Activity of SigB Modulates Virulence Gene Expression in a Murine Staphylococcus aureus Infection Model but Does Not Influence the Host Kidney Gene Expression

Publications

The alternative sigma factor B modulates virulence gene expression in a murine Staphylococcus aureus infection model but does not influence kidney gene expression pattern of the host.

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