The EngCP endo α-N-acetylgalactosaminidase is a virulence factor involved in Clostridium perfringens gas gangrene infections.

Clostridium perfringens is the causative agent of human clostridial myonecrosis; the major toxins involved in this disease are α-toxin and perfringolysin O. The RevSR two-component regulatory system has been shown to be involved in regulating virulence in a mouse myonecrosis model. Previous microarray and RNAseq analysis of a revR mutant implied that factors other than the major toxins may play a role in virulence.

Concurrent Host-Pathogen Transcriptional Responses in a Murine Myonecrosis Infection.

To obtain an insight into host-pathogen interactions in clostridial myonecrosis, we carried out comparative transcriptome analysis of both the bacterium and the host in a murine infection model, which is the first time that such an investigation has been conducted. Analysis of the host transcriptome from infected muscle tissues indicated that many genes were upregulated compared to the results seen with mock-infected mice. These genes were enriched for host defense pathways, including Toll-like receptor (TLR) and Nod-like receptor (NLR) signaling components.

The NEAT Domain-Containing Proteins of Clostridium perfringens Bind Heme.

The ability of a pathogenic bacterium to scavenge iron from its host is important for its growth and survival during an infection. Our studies on C. perfringens gas gangrene strain JIR325, a derivative of strain 13, showed that it is capable of utilizing both human hemoglobin and ferric chloride, but not human holo-transferrin, as an iron source for in vitro growth.

CdtR Regulates TcdA and TcdB Production in Clostridium difficile.

Clostridium difficile is a global health burden and the leading cause of antibiotic-associated diarrhoea worldwide, causing severe gastrointestinal disease and death. Three well characterised toxins are encoded by this bacterium in two genetic loci, specifically, TcdB (toxin B) and TcdA (toxin A) in the Pathogenicity Locus (PaLoc) and binary toxin (CDT) in the genomically distinct CDT locus (CdtLoc). Toxin production is controlled by regulators specific to each locus.

Analysis of the virulence-associated RevSR two-component signal transduction system of Clostridium perfringens.

Clostridium perfringens is a Gram-positive, anaerobic, spore-forming bacterium that causes human gas gangrene (clostridial myonecrosis) and food poisoning. Early studies showed that virulence was regulated by the VirSR two-component signal transduction system. However, our identification of the RevR orphan response regulator indicated that more than one system was involved in controlling virulence.

RNA-seq analysis of virR and revR mutants of Clostridium perfringens.

Background: Clostridium perfringens causes toxin-mediated diseases, including gas gangrene (clostridial myonecrosis) and food poisoning in humans. The production of the toxins implicated in gas gangrene, α-toxin and perfringolysin O, is regulated by the VirSR two-component regulatory system. In addition, RevR, an orphan response regulator, has been shown to affect virulence in the mouse myonecrosis model.

Functional analysis of an feoB mutant in Clostridium perfringens strain 13.

Bacterial pathogens have adopted numerous mechanisms for acquiring iron from host proteins during an infection, including the direct acquisition of ferric iron from heme-associated proteins or from iron-scavenging siderophores. Ferric iron then is transported into the cytosol, where it can be utilized by the bacterial pathogen. Under anaerobic conditions bacteria can also transport ferrous iron using the transmembrane complex FeoAB, but little is known about iron transport systems in anaerobic bacteria such as the pathogenic clostridia.

NanR, a Transcriptional Regulator That Binds to the Promoters of Genes Involved in Sialic Acid Metabolism in the Anaerobic Pathogen Clostridium perfringens.

Among many other virulence factors, Clostridium perfringens produces three sialidases NanH, NanI and NanJ. NanH lacks a secretion signal peptide and is predicted to be an intracellular enzyme, while NanI and NanJ are secreted. Previously, we had identified part of an operon encoding NanE (epimerase) and NanA (sialic acid lyase) enzymes.

Animal models to study the pathogenesis of human and animal Clostridium perfringens infections.

The most common animal models used to study Clostridium perfringens infections in humans and animals are reviewed here. The classical C. perfringens-mediated histotoxic disease of humans is clostridial myonecrosis or gas gangrene and the use of a mouse myonecrosis model coupled with genetic studies has contributed greatly to our understanding of disease pathogenesis.

The pore-forming α-toxin from clostridium septicum activates the MAPK pathway in a Ras-c-Raf-dependent and independent manner.

Clostridium septicum is the causative agent of atraumatic gas gangrene, with α-toxin, an extracellular pore-forming toxin, essential for disease. How C. septicum modulates the host's innate immune response is poorly defined, although α-toxin-intoxicated muscle cells undergo cellular oncosis, characterised by mitochondrial dysfunction and release of reactive oxygen species.

Identification of a two-component signal transduction system that regulates maltose genes in Clostridium perfringens.

Clostridium perfringens is a Gram-positive rod that is widely distributed in nature and is the etiological agent of several human and animal diseases. The complete genome sequence of C. perfringens strain 13 has been determined and multiple two-component signal transduction systems identified.

Utility of the clostridial site-specific recombinase TnpX to clone toxic-product-encoding genes and selectively remove genomic DNA fragments.

TnpX is a site-specific recombinase responsible for the excision and insertion of the transposons Tn4451 and Tn4453 in Clostridium perfringens and Clostridium difficile, respectively. Here, we exploit phenotypic features of TnpX to facilitate genetic mutagenesis and complementation studies. Genetic manipulation of bacteria often relies on the use of antibiotic resistance genes; however, a limited number are available for use in the clostridia.

Regulation of toxin production in the pathogenic clostridia.

The genus Clostridium comprises a large, heterogeneous group of obligate anaerobic, Gram-positive spore forming bacilli. Members of this genus are ubiquitous in the environment and although most species are considered saprophytic, several are pathogenic to both humans and animals. These bacteria cause a variety of diseases including neuroparalysis, gas gangrene, necrotic enteritis, food poisoning, toxic shock syndrome and pseudomembraneous colitis, which in most cases arise as a consequence of the production of potent exotoxins.

Opioid analgesics stop the development of clostridial gas gangrene.

Gas gangrene is a potentially fatal disease that is primarily caused by the ubiquitous, anaerobic bacteria Clostridium perfringens and Clostridium septicum. Treatment is limited to antibiotic therapy, debridement of the infected tissue, and, in severe cases, amputation. The need for new treatment approaches is compelling.

Regulation of sialidase production in Clostridium perfringens by the orphan sensor histidine kinase ReeS.

Clostridium perfringens is ubiquitous in nature and is often found as a commensal of the human and animal gastrointestinal tract. It is the primary etiological agent of clostridial myonecrosis, or gas gangrene, a serious infection that results in extensive tissue necrosis due to the action of one or more potent extracellular toxins. α-toxin and perfringolysin O are the major extracellular toxins involved in the pathogenesis of gas gangrene, but histotoxic strains of C.

Structural and functional analysis of the pore-forming toxin NetB from Clostridium perfringens.

Clostridium perfringens is an anaerobic bacterium that causes numerous important human and animal diseases, primarily as a result of its ability to produce many different protein toxins. In chickens, C. perfringens causes necrotic enteritis, a disease of economic importance to the worldwide poultry industry.

Necrotic enteritis-derived Clostridium perfringens strain with three closely related independently conjugative toxin and antibiotic resistance plasmids.

Unlabelled: The pathogenesis of avian necrotic enteritis involves NetB, a pore-forming toxin produced by virulent avian isolates of Clostridium perfringens type A. To determine the location and mobility of the netB structural gene, we examined a derivative of the tetracycline-resistant necrotic enteritis strain EHE-NE18, in which netB was insertionally inactivated by the chloramphenicol and thiamphenicol resistance gene catP. Both tetracycline and thiamphenicol resistance could be transferred either together or separately to a recipient strain in plate matings.

The cysteine protease α-clostripain is not essential for the pathogenesis of Clostridium perfringens-mediated myonecrosis.

Clostridium perfringens is the causative agent of clostridial myonecrosis or gas gangrene and produces many different extracellular toxins and enzymes, including the cysteine protease α-clostripain. Mutation of the α-clostripain structural gene, ccp, alters the turnover of secreted extracellular proteins in C. perfringens, but the role of α-clostripain in disease pathogenesis is not known.

Regulation of virulence by the RevR response regulator in Clostridium perfringens.

Clostridium perfringens causes clostridial myonecrosis or gas gangrene and produces several extracellular hydrolytic enzymes and toxins, many of which are regulated by the VirSR signal transduction system. The revR gene encodes a putative orphan response regulator that has similarity to the YycF (WalR), VicR, PhoB, and PhoP proteins from other Gram-positive bacteria. RevR appears to be a classical response regulator, with an N-terminal receiver domain and a C-terminal domain with a putative winged helix-turn-helix DNA binding region.

The VirSR two-component signal transduction system regulates NetB toxin production in Clostridium perfringens.

Clostridium perfringens causes several diseases in domestic livestock, including necrotic enteritis in chickens, which is of concern to the poultry industry due to its health implications and associated economic cost. The novel pore-forming toxin NetB is a critical virulence factor in the pathogenesis of this disease. In this study, we have examined the regulation of NetB toxin production.

Functional analysis of the VirSR phosphorelay from Clostridium perfringens.

Toxin production in Clostridium perfringens is controlled by the VirSR two-component signal transduction system, which comprises the VirS sensor histidine kinase and the VirR response regulator. Other studies have concentrated on the elucidation of the genes controlled by this network; there is little information regarding the phosphorelay cascade that is the hallmark of such regulatory systems. In this study, we have examined each step in this cascade, beginning with autophosphorylation of VirS, followed by phosphotransfer from VirS to VirR.

Cross-complementation of Clostridium perfringens PLC and Clostridium septicum alpha-toxin mutants reveals PLC is sufficient to mediate gas gangrene.

Clostridium perfringens and Clostridium septicum are the most common causes of clostridial myonecrosis or gas gangrene. Although they mediate a similar disease pathology, they elaborate functionally very different alpha-toxins. We used a reciprocal complementation approach to assess the contribution of the primary toxin of each species to disease and found that C.

Construction and analysis of chromosomal Clostridium difficile mutants.

Clostridium difficile is an emerging nosocomial pathogen of increasing importance and virulence but our ability to study the molecular mechanisms underlying the pathogenesis of C. difficile-associated disease has been limited because of a lack of tools for its genetic manipulation. We have now developed a reproducible method for the targeted insertional inactivation of chromosomal C.

Skewed genomic variability in strains of the toxigenic bacterial pathogen, Clostridium perfringens.

Clostridium perfringens is a Gram-positive, anaerobic spore-forming bacterium commonly found in soil, sediments, and the human gastrointestinal tract. C. perfringens is responsible for a wide spectrum of disease, including food poisoning, gas gangrene (clostridial myonecrosis), enteritis necroticans, and non-foodborne gastrointestinal infections.

The spatial organization of the VirR boxes is critical for VirR-mediated expression of the perfringolysin O gene, pfoA, from Clostridium perfringens.

The transcriptional regulation of toxin production in the gram-positive anaerobe Clostridium perfringens involves a two-component signal transduction system that comprises the VirS sensor histidine kinase and its cognate response regulator, VirR. Previous studies showed that VirR binds independently to a pair of imperfect direct repeats, now designated VirR box 1 and VirR box 2, located immediately upstream of the promoter of the pfoA gene, which encodes the cholesterol-dependent cytolysin, perfringolysin O. For this study, we introduced mutated VirR boxes into a C.