EHEC outbreak
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ABSTRACT:
PROVIDER: PRJEB28244 | ENA |
REPOSITORIES: ENA
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Project description:Comparative genome sequencing of E.coli EHEC isolated from an outbreak
| PRJEB588 | ENA
Project description:Analysis of total RNA extracted from primary macrophages infected with the bacterial strains of EHEC or EHEC∆Tir. The results showed that Tir might regulate the expression of selected genes.
2018-03-29 | GSE112418 | GEO
Project description:While significant advances have been made in EHEC pathogenesis, we still do not fully understand the impact of environmental stress on EHEC virulence. During the course of infection, EHEC must evade or overcome several biological barriers, the first of which is the gastric acidity encountered during passage through the stomach. EHEC is remarkable in its ability to tolerate this acidity. There are four different acid resistance systems that provide E. coli O157:H7 protection against exposure to low pH (2-2.5). Interestingly, EHEC uses these acid resistance systems differentially for survival in foods versus the bovine intestinal tract. The glutamate-dependent acid-resistance system is thought to offer the best protection below pH 3. Since the infectious dose of EHEC is so low (50-100 organisms), acid resistance becomes an important virulence trait. Studies of EHEC response to acid stress have focused primarily on levels of acid tolerance and the molecular basis of tolerance. However, the impact of acid stress on EHEC virulence is less well understood. In the related pathogen, EPEC, the plasmid-encoded regulator, Per, that regulates expression of many EPEC virulence factors, is regulated negatively at pH 5.5 and positively at pH 8.0, suggesting that virulence gene expression is repressed during mild acid stress and enhanced in alkaline pH typical of the small intestine. Expression of EPEC type III secreted factors involved in A/E lesion formation has been shown to be influenced by factors including culture media, iron and calcium levels. Protein secretion was inhibited at pH 6 and 8. In a third study, a gadE (encoding acid resistance regulator) mutation resulted in increased adhesion of E.coli O157:H7 to colonic epithelial cells, suggesting negative regulation of one or more adhesins. Other studies have reported that shiga toxin production is sensitive to culture conditions including pH. However, there are no studies of EHEC virulence changes after more severe acid stress nor studies linking stressed EHEC virulence phenotype with transcriptional changes. The goal of this study was to determine how acid stress affects EHEC virulence properties and through microarray analysis, define the genetic basis for these changes. Understanding how acid stress modulates the virulence potential of this pathogen is essential for delineating the pathogenesis of disease caused by EHEC infection and may offer novel approaches to prevent and treat EHEC infections.
2009-06-26 | GSE14069 | GEO
Project description:Enterohaemorrhagic Escherichia coli (EHEC) is an emerging pathogen that causes diarrhea and heamolytic uremic syndrome. Expression of genes associated to pathogenicity is strictly regulated by environmental factors. Since short chian fatty acids (SCFAs) are present in intestinal tract which is a target of EHEC infection, we investigated the response of EHEC genes to SCFAs, such as acetate, propionate and butyrate. Keywords: Culture condition
2008-11-01 | GSE12903 | GEO
Project description:EHEC is a food-borne pathogen that colonizes human GI tract and leads to infection. To understand the process of colonization and to decipher if any factors secreted by intestinal epithelial cells help EHEC during the infection process, we studied expression of EHEC virulence gene expression when exposed to intestinal epithelial cell conditioned medium. In our study, we observed that exposure to epithelial cell conditioned medium for 1 h and 3 h increases expression of 32 out of 41 EHEC LEE virulence genes. In addition, expression of the shiga toxin 1 (Stx1) gene is up-regulated at 1 h of exposure. Also, 17 genes encoded by prophage 933W, including those for Stx2, are also upregulated at both time-points. The increase in 933W prophage expression is mirrored by a 2.7-fold increase in intracellular Stx2 phage titers. Consistent with the increase in virulence gene expression, we observed a 5-fold increase in EHEC attachment to epithelial cells when exposed to conditioned medium, suggesting that EHEC utilizes host cell molecules to increase virulence and infectivity. The molecule(s) responsible for increased EHEC virulence is heat-sensitive as heating the conditioned medium to 95oC abolishes the increase in attachment to epithelial cells. A similar decrease was observed when the conditioned medium was treated with proteinase-K to degrade the proteins. The secreted molecule(s) was found to be larger than 3 kDa and strongly suggests that the HCT-8 secreted molecule that increases EHEC virulence and colonization is a protein-based molecule. Affymetrix E. coli Genome 2.0 Arrays were used to determine the changes in EHEC virulence gene expression on exposure to intestinal epithelial cell-secreted factors (through growth in conditioned medium).
2012-10-04 | GSE22285 | GEO
Project description:The first goal of the study was to identify genes differentially regulated by MavR in EHEC strain 86-24. The second goal was to identify direct targets of MavR through the MAPS protocol.
2021-09-16 | GSE166491 | GEO
Project description:Enterohemorrhagic E. coli (EHEC) colonizes the large intestine and causes attaching and effacing lesions (AE). Most of the genes involved in the formation of AE lesions are encoded within a chromosomal pathogenicity island termed the Locus of Enterocyte Effacement (LEE). The LysR-like transcriptional factor QseA regulates the LEE by binding directly to the regulatory region of ler. Here, we performed transcriptome analyses comparing WT EHEC and the isogenic qseA mutant in order to elucidate the extent of QseA’s role in gene regulation in EHEC. The following results compare genes that were up-regulated and down-regulated ! 2-fold in the qseA mutant strain compared to the WT strain. At mid-exponential growth, 222 genes were up-regulated and 1874 were downregulated. At late-exponential growth, a total of 55 genes were up-regulated and 605 genes were down-regulated. During mid-exponential growth, QseA represses its own transcription, whereas during late-logarithmic growth, QseA activates expression of the LEE genes as well as non-LEE encoded effector proteins. During both growth phases, several genes carried in O-islands, were activated by QseA, whereas genes involved in cell metabolism were repressed. We also performed electrophoretic mobility shift assays, competition experiments, and DNAseI footprints, and the results suggested that QseA directly binds both the ler proximal and distal promoters, its own promoter, as well as promoters of genes encoded in EHEC-specific O-islands. Additionally, we mapped the transcriptional start site of qseA, leading to the identification of two promoter sequences. Taken together, these results indicate that QseA acts as a global regulator in EHEC, coordinating expression of virulence genes.
2010-09-07 | GSE18118 | GEO
Project description:A study on the effects of an sdiA mutant and the AHL molecule on the virulence of EHEC
2010-04-09 | GSE13562 | GEO
Project description:Global regulation of the effects of deletion of phage cro gene in EHEC
2016-09-29 | GSE86271 | GEO
Project description:Enterohaemorrhagic Escherichia coli (EHEC) is an emerging pathogen that causes diarrhea and heamolytic uremic syndrome. Expression of genes associated to pathogenicity is strictly regulated by environmental factors. Since short chian fatty acids (SCFAs) are present in intestinal tract which is a target of EHEC infection, we investigated the response of EHEC genes to SCFAs, such as acetate, propionate and butyrate. Keywords: Culture condition 3 sets of comparison between transcription profiles in EHEC growing in the presence of acetate, propionate or butyrate against EHEC growing in the presence of NaCl. Labelling of cDNA and hybridization were performed twice with independently prepared RNAs.
2010-05-17 | E-GEOD-12903 | biostudies-arrayexpress