The SaeR/S Gene Regulatory System is Essential for Innate Immune Evasion by Staphylococcus aureus
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ABSTRACT:
ORGANISM(S): Staphylococcus epidermidis RP62A Rickettsia rickettsii Borreliella burgdorferi B31 Coxiella burnetii RSA 493 Granulibacter bethesdensis Staphylococcus epidermidis ATCC 12228 Coxiella burnetii Chlamydia muridarum Chlamydia trachomatis D/UW-3/CX Staphylococcus haemolyticus JCSC1435 Staphylococcus aureus Chlamydia pneumoniae AR39 Staphylococcus aureus subsp. aureus MW2 Chlamydia caviae GPIC
PROVIDER: GSE15067 | GEO | 2010/02/23
SECONDARY ACCESSION(S): PRJNA114843
REPOSITORIES: GEO
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Project description:Methicillin-resistant Staphylococcus aureus (MRSA) is problematic both in hospitals and the community. Currently, we have limited understanding of mechanisms of innate immune evasion used by S. aureus. To that end, we created an isogenic deletion mutant in strain MW2 (USA400) of the saeR/S two-component gene regulatory system and studied its role in mouse models of pathogenesis and during human neutrophil interaction. In this study, we demonstrate saeR/S plays a distinct role in S. aureus pathogenesis and is vital for virulence of MW2 in a mouse model of sepsis. Moreover, deletion of saeR/S significantly impaired survival of MW2 in human blood and after neutrophil phagocytosis. Microarray analysis of genes influenced by saeR/S demonstrated SaeR/S of MW2 influences a wide variety of genes with diverse biological functions. These data shed new insight into how virulence is regulated in S. aureus and associates a specific staphylococcal gene-regulatory system with invasive staphylococcal disease. Wild type control vs mutant at two different growth phases
2010-05-14 | E-GEOD-15067 | biostudies-arrayexpress
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Project description:Neutrophil lysis after phagocytosis is a process potentially important in the pathogenesis of community-associated methicillin-resistant S. aureus (CA-MRSA) infection. The mechanism for this process is not currently known. Therefore, to better understand CA-MRSA virulence we used human oligonucleotide microarrays to investigate the mechanism underlying enhanced PMN lysis that occurs after phagocytosis of CA-MRSA. In order to examine the effect of S. aureus on the neutrophil transcriptome and to elucidate any possible differences in this effect between hospital- and community-associated S. aureus, we performed microarray expression analysis on human neutrophils treated with hospital- and community-associated S. aureus. Polymorphonuclear leukocytes (PMNs) were isolated from the blood of healthy donors. Control and S. aureus-exposed PMNs were incubated at 37C for 1, 2, 3 or 6 hours.
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Project description:Staphylococcus aureus is a Gram-positive human pathogen causing a variety of human diseases in both hospital and community settings. This bacterium is so closely associated with prophages that it is rare to find S. aureus isolates without prophages. Two phages are known to be important for staphylococcal virulence: the beta-hemolysin (hlb) converting phage and the Panton-Valentine Leukocidin (PVL) converting phage. The hlb-converting phage is found in more than 90% of clinical isolates of S. aureus. This phage produces exotoxins and immune modulatory molecules, which inhibit human innate immune responses. The PVL-converting phage produces the two-component exotoxin PVL, which can kill human leucocytes. This phage is wide-spread among community-associated methicillin resistant S. aureus (CA-MRSA). It also shows strong association with soft tissue infections and necrotizing pneumonia. Several lines of evidence suggest that staphylococcal prophages increase bacterial virulence not only by providing virulence factors but also by altering bacterial gene expression: 1) Transposon insertion into prophage regulatory genes, but not into the genes of virulence factors, reduced S. aureus killing of Caenorhabditis elegans.; 2) Although the toxins and immune modulatory molecules encoded by the hlb- converting phages do not function in the murine system, deletion of ϕNM3, the hlb-converting phage in S. aureus Newman, reduced staphylococcal virulence in the murine abscess formation model. 3) In a preliminary microarray experiment, prophages in S. aureus Newman altered the expression of more than 300 genes. In this research proposal, using microarray and high-throughput quantitative RT-PCR (qRT-PCR) technologies, we will identify the effects of the two important staphylococcal phages on the gene expression of S. aureus in both in vitro and in vivo conditions. This project is intended to be completed within one year. All the data – microarray, qRT-PCR and all the primer sequences- will be made available to public 6 month after completion. Data from this project will help us to understand the role of prophages in the S. aureus pathogenesis and can lead to development of a strategy to interfere with the pathogenesis process.
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