Project description:This study primarily shows the transcripts for all genes possibly involved in uptake of C. difficile TcdB. The long term effect of the second receptor binding domain (aa 1101-1873) of TcdB (2 µg/ml) on Hep-2 cells was investigated after 72 hours of incubation.
Project description:Clostridium difficile (Cd) is a gram-positive, spore-forming bacterium and the primary cause of nosocomial diarrhea and pseudomembranous colitis. The pathogenicity of Cd has been linked to its production of TcdA and TcdB. While they cause fluid secretion, inflammation, and colonic damage, their respective and synergistic roles have been difficult to ascertain. In infection animal model, TcdB has been demonstrated to be a key virulence factor, and TcdB causes obvious damage in human and porcine colonic explants. Using the colonic epithelia derived from cloned colonic stem cells, we have developed a model to test the response to TcdB. Epithelia generated in air-liquid interface cultures from cloned transverse colon stem cells were challenged with TcdB at different concentrations and durations.
Project description:Toxin A and B from Clostridium difficile are the primary virulence factors in Clostridium difficile disease. The changes in gene transcription of human colon epithelial cells were investigated in vitro in order to better understand the many effects of both toxins. HCT-8 cells were treated with 100 ng/ml of either Toxin A or B (TcdA or TcdB). RNA was isolated 2, 6, and 24 hours after addition of toxin from untreated and toxin-treated cells.
Project description:Clostridium difficile is an important nosocomial pathogen and the leading cause of hospital-acquired diarrhea. Antibiotic use is the primary risk factor for the development of C. difficile-associated disease because it disrupts normal protective gut flora and enables C. difficile to colonize the colon. C. difficile damages host tissue by secreting toxins and disseminates by forming spores. The toxin-encoding genes, tcdA and tcdB are part of a pathogenicity locus, which also encodes the gene tcdR that codes for the toxin genes positive regulator. TcdR is an alternate sigma factor that initiates transcription of tcdA and tcdB at their promoters. Alternative sigma factors are known to regulate virulence and virulence associated genes in many pathogenic bacteria. We created a tcdR mutant in the epidemic-type C. difficile R20291 strain in an attempt to identify the global role of tcdR. A site-directed mutation in tcdR affected both toxin production and sporulation in C. difficile R20291. Spores derived from the tcdR mutant were found to be mildly temperature sensitive. Moreover, nearly two fold more taurocholate was needed to germinate spores from the tcdR mutant than the spores prepared from the wild-type parent strain. Comparison of the tcdR mutant transcriptome with the parent strain revealed many differentially expressed late sporulation genes in the tcdR mutant. These data suggests that gene regulatory networks of toxin production and sporulation in Clostridium difficile are linked with each other.
Project description:Transcriptional analysis of Clostridium difficile R20291 in biofilm formation, planktonic state and grown on blood agar RNA sequencing was performed on Clostridium difficile R20291 in three different conditions: Biofilm formation, plantonic state and grown on blood agar plates. Each condtion has 3 replicates.
Project description:Toxin A (TcdA) and Toxin B (TcdB), of the pathogen Clostridium difficile, are virulence factors that cause gross pathologic changes (e.g. inflammation, secretion, and diarrhea) in the infected host, yet the molecular and cellular pathways leading to observed host responses are poorly understood. To address this gap, TcdA and/or TcdB were injected into the ceca of mice and the genome-wide transcriptional response of epithelial layer cells was examined. Bioinformatic analysis of gene expression identified sets of cooperatively expressed genes. Further analysis of inflammation associated genes revealed dynamic chemokine responses. In total, 32 samples were analyzed (one microarray per mouse). The sample groups are separated by two factors: Toxin (TcdA, TcdB, TcdA+TcdB, or Sham injection) and endpoint (2, 6, or 16h). TcdA+B at 16h was not included, leaving 11 sample groups. Each sample group included biological triplicates, except TcdA+TcdB at 6h (one array) and Sham injection at 16h (four arrays).
Project description:Toxin A (TcdA) and Toxin B (TcdB), of the pathogen Clostridium difficile, are virulence factors that cause gross pathologic changes (e.g. inflammation, secretion, and diarrhea) in the infected host, yet the molecular and cellular pathways leading to observed host responses are poorly understood. To address this gap, TcdA and/or TcdB were injected into the ceca of mice and the genome-wide transcriptional response of epithelial layer cells was examined. Bioinformatic analysis of gene expression identified sets of cooperatively expressed genes. Further analysis of inflammation associated genes revealed dynamic chemokine responses.
Project description:The incidence of Clostridium difficile infection has been steadily rising over the past decade. Its increased rate is associated with the specific NAP1/BI/027 strains which are “hypervirulent” and have led to several large outbreaks since their emergence. However, the relation between their outbreaks and virulence regulation mechanisms remains unclear. It has been reported that the major virulence factor TcdA and TcdB in C. difficile could be repressed by cysteine. Here, we investigated functional and virulence-associated regulation of C. difficile R20291 in response to cysteine stress by using a time-resolved genome-wide transcriptional analysis. Dramatic changes of gene expression in C. difficile were revealed in functional categories related to transport, metabolism, and regulators under cysteine stress during different phases of growth.
Project description:Toxin A and B from Clostridium difficile are the primary virulence factors in Clostridium difficile disease. The changes in gene transcription of human colon epithelial cells were investigated in vitro in order to better understand the many effects of both toxins.