scholarly journals The VirS/VirR Two-Component System Regulates the Anaerobic Cytotoxicity, Intestinal Pathogenicity, and Enterotoxemic Lethality of Clostridium perfringens Type C Isolate CN3685

mBio ◽  
2011 ◽  
Vol 2 (1) ◽  
Author(s):  
Menglin Ma ◽  
Jorge Vidal ◽  
Juliann Saputo ◽  
Bruce A. McClane ◽  
Francisco Uzal
Keyword(s):  
Clostridium Perfringens ◽  
Regulatory System ◽  
Gas Gangrene ◽  
Necrotic Enteritis ◽  
Vegetative Cells ◽  
Content Type ◽  
Two Component ◽  
Type C ◽  
Beta Toxin

ABSTRACT Clostridium perfringens vegetative cells cause both histotoxic infections (e.g., gas gangrene) and diseases originating in the intestines (e.g., hemorrhagic necrotizing enteritis or lethal enterotoxemia). Despite their medical and veterinary importance, the molecular pathogenicity of C. perfringens vegetative cells causing diseases of intestinal origin remains poorly understood. However, C. perfringens beta toxin (CPB) was recently shown to be important when vegetative cells of C. perfringens type C strain CN3685 induce hemorrhagic necrotizing enteritis and lethal enterotoxemia. Additionally, the VirS/VirR two-component regulatory system was found to control CPB production by CN3685 vegetative cells during aerobic infection of cultured enterocyte-like Caco-2 cells. Using an isogenic virR null mutant, the current study now reports that the VirS/VirR system also regulates CN3685 cytotoxicity during infection of Caco-2 cells under anaerobic conditions, as found in the intestines. More importantly, the virR mutant lost the ability to cause hemorrhagic necrotic enteritis in rabbit small intestinal loops. Western blot analyses demonstrated that the VirS/VirR system mediates necrotizing enteritis, at least in part, by controlling in vivo CPB production. In addition, vegetative cells of the isogenic virR null mutant were, relative to wild-type vegetative cells, strongly attenuated in their lethality in a mouse enterotoxemia model. Collectively, these results identify the first regulator of in vivo pathogenicity for C. perfringens vegetative cells causing disease originating in the complex intestinal environment. Since VirS/VirR also mediates histotoxic infections, this two-component regulatory system now assumes a global role in regulating a spectrum of infections caused by C. perfringens vegetative cells. IMPORTANCE Clostridium perfringens is an important human and veterinary pathogen. C. perfringens vegetative cells cause both histotoxic infections, e.g., traumatic gas gangrene, and infections originating when this bacterium grows in the intestines. The VirS/VirR two-component regulatory system has been shown to control the pathogenicity of C. perfringens type A strains in a mouse gas gangrene model, but there is no understanding of pathogenicity regulation when C. perfringens vegetative cells cause disease originating in the complex intestinal environment. The current study establishes that VirS/VirR controls vegetative cell pathogenicity when C. perfringens type C isolates cause hemorrhagic necrotic enteritis and lethal enterotoxemia (i.e., toxin absorption from the intestines into the circulation, allowing targeting of internal organs). This effect involves VirS/VirR-mediated regulation of beta toxin production in vivo. Therefore, VirS/VirR is the first identified global in vivo regulator controlling the ability of C. perfringens vegetative cells to cause gas gangrene and, at least some, intestinal infections.

scholarly journals Evidence That VirS Is a Receptor for the Signaling Peptide of the Clostridium perfringens Agr-like Quorum Sensing System

mBio ◽  
2020 ◽  
Vol 11 (5) ◽  
Author(s):  
Jihong Li ◽  
Bruce A. McClane
Keyword(s):  
Quorum Sensing ◽  
Clostridium Perfringens ◽  
Regulatory System ◽  
Extracellular Loop ◽  
Accessory Gene ◽  
Content Type ◽  
Membrane Sensor ◽  
Two Component ◽  
Sensor Protein ◽  
Beta Toxin

ABSTRACT Since both the Agr (accessory gene regulator)-like quorum sensing (QS) system and VirS/VirR (VirS/R) two-component regulatory system of Clostridium perfringens positively regulate production of several toxins, including C. perfringens beta toxin (CPB), it has been hypothesized the VirS membrane sensor protein is an Agr-like QS signaling peptide (SP) receptor. To begin evaluating whether VirS is an SP receptor, this study sequenced the virS gene in C. perfringens strains CN3685 and CN1795 because it was reported that agrB mutants of both strains increase CPB production in response to the pentapeptide 5R, likely the natural SP, but only the CN3685 agrB mutant responds to 8R, which is 5R plus a 3-amino-acid tail. This sequencing identified differences between the predicted VirS extracellular loop 2 (ECL2) of CN3685 versus that of CN1795. To explore if those ECL2 differences explain strain-related variations in SP sensitivity and support VirS as an SP receptor, virS agrB double-null mutants of each strain were complemented to swap which VirS protein they produce. CPB Western blotting showed that this complementation changed the natural responsiveness of each strain to 8R. A pulldown experiment using biotin-5R demonstrated that VirS can bind SP. To further support VirS:SP binding and to identify a VirS binding site for SP, a 14-mer peptide corresponding to VirS ECL2 was synthesized. This ECL2 peptide inhibited 5R signaling to agrB mutant and wild-type strains. This inhibition was specific, since a single N to D substitution in the ECL2 peptide abrogated these effects. Collectively, these results support VirS as an important SP receptor and may assist development of therapeutics. IMPORTANCE C. perfringens beta toxin (CPB) is essential for the virulence of type C strains, a common cause of fatal necrotizing enteritis and enterotoxemia in humans and domestic animals. Production of CPB, as well as several other C. perfringens toxins, is positively regulated by both the Agr-like QS system and the VirS/R two-component regulatory system. This study presents evidence that the VirS membrane sensor protein is a receptor for the AgrD-derived SP and that the second extracellular loop of VirS is important for SP binding. Understanding interactions between SP and VirS improves knowledge of C. perfringens pathogenicity and may provide insights for designing novel strategies to reduce C. perfringens toxin production during infections.

scholarly journals Genotypic and Phenotypic Characterization of Clostridium perfringens Isolates from Darmbrand Cases in Post-World War II Germany

2012 ◽  
Vol 80 (12) ◽  
pp. 4354-4363 ◽  
Author(s):  
Menglin Ma ◽  
Jihong Li ◽  
Bruce A. McClane
Keyword(s):  
World War Ii ◽  
Heat Resistance ◽  
Clostridium Perfringens ◽  
Type A ◽  
World War ◽  
Content Type ◽  
Post World War Ii ◽  
Heat Resistant ◽  
Type C ◽  
Beta Toxin

ABSTRACTClostridium perfringenstype C strains are the only non-type-A isolates that cause human disease. They are responsible for enteritis necroticans, which was termed Darmbrand when occurring in post-World War II Germany. Darmbrand strains were initially classified as type F because of their exceptional heat resistance but later identified as type C strains. Since only limited information exists regarding Darmbrand strains, this study genetically and phenotypically characterized seven 1940s era Darmbrand-associated strains. Results obtained indicated the following. (i) Five of these Darmbrand isolates belong to type C, carry beta-toxin (cpb) and enterotoxin (cpe) genes on large plasmids, and express both beta-toxin and enterotoxin. The other two isolates arecpe-negative type A. (ii) All seven isolates produce highly heat-resistant spores withD100values (the time that a culture must be kept at 100°C to reduce its viability by 90%) of 7 to 40 min. (iii) All of the isolates surveyed produce the same variant small acid-soluble protein 4 (Ssp4) made by type A food poisoning isolates with a chromosomalcpegene that also produce extremely heat-resistant spores. (iv) The Darmbrand isolates share a genetic background with type A chromosomal-cpe-bearing isolates. Finally, it was shown that both thecpeandcpbgenes can be mobilized in Darmbrand isolates. These results suggest thatC. perfringenstype A and C strains that cause human food-borne illness share a spore heat resistance mechanism that likely favors their survival in temperature-abused food. They also suggest possible evolutionary relationships between Darmbrand strains and type A strains carrying a chromosomalcpegene.

scholarly journals Synergistic Effects of Clostridium perfringens Enterotoxin and Beta Toxin in Rabbit Small Intestinal Loops

2014 ◽  
Vol 82 (7) ◽  
pp. 2958-2970 ◽  
Author(s):  
Menglin Ma ◽  
Abhijit Gurjar ◽  
James R. Theoret ◽  
Jorge P. Garcia ◽  
Juliann Beingesser ◽  
...  
Keyword(s):  
Clostridium Perfringens ◽  
Synergistic Effects ◽  
Fluid Accumulation ◽  
Content Type ◽  
Positive Type ◽  
Intestinal Infections ◽  
Type C ◽  
Small Intestinal ◽  
Beta Toxin ◽  
Enteritis Necroticans

ABSTRACTThe ability ofClostridium perfringenstype C to cause human enteritis necroticans (EN) is attributed to beta toxin (CPB). However, many EN strains also expressC. perfringensenterotoxin (CPE), suggesting that CPE could be another contributor to EN. Supporting this possibility, lysate supernatants from modified Duncan-Strong sporulation (MDS) medium cultures of three CPE-positive type C EN strains caused enteropathogenic effects in rabbit small intestinal loops, which is significant since CPE is produced only during sporulation and sinceC. perfringenscan sporulate in the intestines. Consequently, CPE and CPB contributions to the enteropathogenic effects of MDS lysate supernatants of CPE-positive type C EN strain CN3758 were evaluated using isogeniccpbandcpenull mutants. While supernatants of wild-type CN3758 MDS lysates induced significant hemorrhagic lesions and luminal fluid accumulation, MDS lysate supernatants of thecpbandcpemutants caused neither significant damage nor fluid accumulation. This attenuation was attributable to inactivating these toxin genes since complementing thecpemutant or reversing thecpbmutation restored the enteropathogenic effects of MDS lysate supernatants. Confirming that both CPB and CPE are needed for the enteropathogenic effects of CN3758 MDS lysate supernatants, purified CPB and CPE at the same concentrations found in CN3758 MDS lysates also acted together synergistically in rabbit small intestinal loops; however, only higher doses of either purified toxin independently caused enteropathogenic effects. These findings provide the first evidence for potential synergistic toxin interactions duringC. perfringensintestinal infections and support a possible role for CPE, as well as CPB, in some EN cases.

scholarly journals Identifying the Basis for VirS/VirR Two-Component Regulatory System Control of Clostridium perfringens Beta Toxin Production

2021 ◽  
Author(s):  
Iman Mehdizadeh Gohari ◽  
Jihong Li ◽  
Bruce A. McClane
Keyword(s):  
Quorum Sensing ◽  
Clostridium Perfringens ◽  
Regulatory System ◽  
Toxin Production ◽  
Start Codon ◽  
Binding Motif ◽  
Type B ◽  
Regulatory Cascade ◽  
Two Component ◽  
Beta Toxin

Clostridium perfringens toxin production is often regulated by the Agr-like quorum sensing (QS) system signaling the VirS/VirR two-component regulatory system (TCRS), which consists of the VirS membrane sensor histidine kinase and the VirR response regulator. VirS/VirR is known to directly control expression of some genes by binding to a DNA binding motif consisting of two VirR boxes located within 500 bp of the target gene start codon. Alternatively, the VirS/VirR system can indirectly regulate production levels of other proteins by increasing expression of a small regulatory RNA (VR-RNA). Previous studies demonstrated that beta toxin (CPB) production by C. perfringens type B and C strains is positively-regulated by both the Agr-like QS and VirS/VirR TCRS, but the mechanism has been unclear. The current study first inactivated the vrr gene encoding VR-RNA to show that VirS/VirR regulation of cpb expression does not involve VR-RNA. Subsequently, bioinformatic analyses identified a potential VirR binding motif, along with a predicted strong promoter, ∼1.4 kb upstream of the cpb open reading frame (ORF). Two insertion sequences were present between this VirR binding motif/promoter region and the cpb ORF. PCR screening of a collection of strains carrying cpb showed that the presence and sequence of this VirR binding motif/promoter is highly conserved among CPB-producing strains. RT-PCR and a GusA reporter assay showed this VirR binding motif is important for regulating CPB producion. These findings indicate that VirS/VirR directly regulates cpb expression via VirS binding to a VirR binding motif located unusually distant from the cpb start codon. IMPORTANCE Clostridium perfringens beta toxin (CPB) is only produced by type B and C strains. Production of CPB is essential for the pathogenesis of type C-associated infections, which include hemorrhagic necrotizing enteritis and enterotoxemia in both humans and animals. In addition, CPB can synergize with other toxins during C. perfringens gastrointestinal diseases. CPB toxin production is cooperatively regulated by the Agr-like quorum sensing (QS) system and the VirS/VirR two-component regulatory system. This study now reports that the VirS/VirR regulatory cascade directly controls expression of the cpb gene via a process involving a VirR box binding motif located unusually far (∼1.4 kb) upstream of the cpb ORF. This study provides a better understanding of the regulatory mechanisms for CPB production by the VirS/VirR regulatory cascade.

scholarly journals Epsilon-Toxin Production by Clostridium perfringens Type D Strain CN3718 Is Dependent upon the agr Operon but Not the VirS/VirR Two-Component Regulatory System

mBio ◽  
2011 ◽  
Vol 2 (6) ◽  
Author(s):  
Jianming Chen ◽  
Julian I. Rood ◽  
Bruce A. McClane
Keyword(s):  
Quorum Sensing ◽  
Clostridium Perfringens ◽  
Regulatory System ◽  
Toxin Production ◽  
Broth Culture ◽  
Type B ◽  
Content Type ◽  
Type D ◽  
Two Component ◽  
Epsilon Toxin

ABSTRACT Clostridium perfringens type B and D strains cause enterotoxemias and enteritis in livestock after proliferating in the intestines and producing epsilon-toxin (ETX), alpha-toxin (CPA), and, usually, perfringolysin O (PFO). Although ETX is one of the most potent bacterial toxins, the regulation of ETX production by type B or D strains remains poorly understood. The present work determined that the type D strain CN3718 upregulates production of ETX upon close contact with enterocyte-like Caco-2 cells. This host cell-induced upregulation of ETX expression was mediated at the transcriptional level. Using an isogenic agrB null mutant and complemented strain, the agr operon was shown to be required when CN3718 produces ETX in broth culture or, via a secreted signal consistent with a quorum-sensing (QS) effect, upregulates ETX production upon contact with host cells. These findings provide the first insights into the regulation of ETX production, as well as additional evidence that the Agr-like QS system functions as a global regulator of C. perfringens toxin production. Since it was proposed previously that the Agr-like QS system regulates C. perfringens gene expression via the VirS/VirR two-component regulatory system, an isogenic virR null mutant of CN3718 was constructed to evaluate the importance of VirS/VirR for CN3718 toxin production. This mutation affected production of CPA and PFO, but not ETX, by CN3718. These results provide the first indication that C. perfringens toxin expression regulation by the Agr-like quorum-sensing system may not always act via the VirS/VirR two-component system. IMPORTANCE Mechanisms by which Clostridium perfringens type B and D strains regulate production of epsilon-toxin (ETX), a CDC class B select toxin, are poorly understood. Production of several other toxins expressed by C. perfringens is wholly or partially regulated by both the Agr-like quorum-sensing (QS) system and the VirS/VirR two-component regulatory system, so the present study tested whether ETX expression by type D strain CN3718 also requires these regulatory systems. The agr operon was shown to be essential for signaling CN3718 to produce ETX in broth culture or to upregulate ETX production upon close contact with enterocyte-like Caco-2 cells, which may have pathogenic relevance since ETX is produced intestinally. However, ETX production remained at wild-type levels after inactivation of the VirS/VirR system in CN3718. These findings provide the first information regarding regulation of ETX production and suggest Agr-like QS toxin production regulation in C. perfringens does not always require the VirS/VirR system.

scholarly journals The Agr-Like Quorum-Sensing System Is Important for Clostridium perfringens Type A Strain ATCC 3624 To Cause Gas Gangrene in a Mouse Model

mSphere ◽  
2020 ◽  
Vol 5 (3) ◽  
Author(s):  
Mauricio A. Navarro ◽  
Jihong Li ◽  
Juliann Beingesser ◽  
Bruce A. McClane ◽  
Francisco A. Uzal
Keyword(s):  
Quorum Sensing ◽  
Mouse Model ◽  
Clostridium Perfringens ◽  
Regulatory System ◽  
Type A ◽  
Gas Gangrene ◽  
Null Mutant ◽  
Wild Type ◽  
Content Type

ABSTRACT Clostridium perfringens type A is involved in gas gangrene in humans and animals. Following a traumatic injury, rapid bacterial proliferation and exotoxin production result in severe myonecrosis. C. perfringens alpha toxin (CPA) and perfringolysin (PFO) are the main virulence factors responsible for the disease. Recent in vitro studies have identified an Agr-like quorum-sensing (QS) system in C. perfringens that regulates the production of both toxins. The system is composed of an AgrB membrane transporter and an AgrD peptide that interacts with a two-component regulatory system in response to fluctuations in the cell population density. In addition, a synthetic peptide named 6-R has been shown to interfere with this signaling mechanism, affecting the function of the Agr-like QS system in vitro. In the present study, C. perfringens type A strain ATCC 3624 and an isogenic agrB-null mutant were tested in a mouse model of gas gangrene. When mice were intramuscularly challenged with 106 CFU of wild-type ATCC 3624, severe myonecrosis and leukocyte aggregation occurred by 4 h. Similar numbers of an agrB-null mutant strain produced significantly less severe changes in the skeletal muscle of challenged mice. Complementation of the mutant to regain agrB expression restored virulence to wild-type levels. The burdens of all three C. perfringens strains in infected muscle were similar. In addition, animals injected intramuscularly with wild-type ATCC 3624 coincubated with the 6-R peptide developed less severe microscopic changes. This study provides the first in vivo evidence that the Agr-like QS system is important for C. perfringens type A-mediated gas gangrene. IMPORTANCE Clostridium perfringens type A strains produce toxins that are responsible for clostridial myonecrosis, also known as gas gangrene. Toxin production is regulated by an Agr-like quorum-sensing (QS) system that responds to changes in cell population density. In this study, we investigated the importance of this QS system in a mouse model of gas gangrene. Mice challenged with a C. perfringens strain with a nonfunctional regulatory system developed less severe changes in the injected skeletal muscle compared to animals receiving the wild-type strain. In addition, a synthetic peptide was able to decrease the effects of the QS in this disease model. These studies provide new understanding of the pathogenesis of gas gangrene and identified a potential therapeutic target to prevent the disease.

scholarly journals Clostridium perfringens type C necrotic enteritis in pigs: diagnosis, pathogenesis, and prevention

2020 ◽  
Vol 32 (2) ◽  
pp. 203-212 ◽  
Author(s):  
Horst Posthaus ◽  
Sonja Kittl ◽  
Basma Tarek ◽  
Julia Bruggisser
Keyword(s):  
Small Intestine ◽  
Clostridium Perfringens ◽  
Vascular Endothelial Cells ◽  
Necrotic Enteritis ◽  
Vascular Endothelial ◽  
Intestinal Epithelial ◽  
Long Time ◽  
Type C ◽  
Mucosal Necrosis ◽  
Beta Toxin

Clostridium perfringens type C causes severe and lethal necrotic enteritis (NE) in newborn piglets. NE is diagnosed through a combination of pathology and bacteriologic investigations. The hallmark lesion of NE is deep, segmental mucosal necrosis with marked hemorrhage of the small intestine. C. perfringens can be isolated from intestinal samples in acute cases but it is more challenging to identify pathogenic strains in subacute-to-chronic cases. Toxinotyping or genotyping is required to differentiate C. perfringens type C from commensal type A strains. Recent research has extended our knowledge about the pathogenesis of the disease, although important aspects remain to be determined. The pathogenesis involves rapid overgrowth of C. perfringens type C in the small intestine, inhibition of beta-toxin (CPB) degradation by trypsin inhibitors in the colostrum of sows, and most likely initial damage to the small intestinal epithelial barrier. CPB itself acts primarily on vascular endothelial cells in the mucosa and can also inhibit platelet function. Prevention of the disease is achieved by immunization of pregnant sows with C. perfringens type C toxoid vaccines, combined with proper sanitation on farms. For the implementation of prevention strategies, it is important to differentiate between disease-free and pathogen-free status of a herd. The latter is more challenging to maintain, given that C. perfringens type C can persist for a long time in the environment and in the intestinal tract of adult animals and thus can be distributed via clinically and bacteriologically inapparent carrier animals.

scholarly journals Phosphorylation at the D53 but Not the T65 Residue of CovR Determines the Repression ofrggandspeBTranscription inemm1- andemm49-Type Group A Streptococci

2018 ◽  
Vol 201 (4) ◽  
Author(s):  
Chuan Chiang-Ni ◽  
Chih-Yuan Kao ◽  
Chih-Yun Hsu ◽  
Cheng-Hsun Chiu
Keyword(s):  
Intergenic Region ◽  
Dominant Role ◽  
Transcriptional Repressor ◽  
Regulatory System ◽  
Independent Manner ◽  
Content Type ◽  
Two Component ◽  
Group A ◽  
Direct Binding

ABSTRACTCovR/CovS is a two-component regulatory system in group AStreptococcusand primarily acts as a transcriptional repressor. The D53 residue of CovR (CovRD53) is phosphorylated by the sensor kinase CovS, and the phosphorylated CovRD53protein binds to the intergenic region ofrgg-speBto inhibitspeBtranscription. Nonetheless, the transcription ofrggandspeBis suppressed incovSmutants. The T65 residue of CovR is phosphorylated in a CovS-independent manner, and phosphorylation at the D53 and T65 residues of CovR is mutually exclusive. Therefore, how phosphorylation at the D53 and T65 residues of CovR contributes to the regulation ofrggandspeBexpression was elucidated. The transcription ofrggandspeBwas suppressed in the strain that cannot phosphorylate the D53 residue of CovR (CovRD53Amutant) but restored to levels similar to those of the wild-type strain in the CovRT65Amutant. Nonetheless, inactivation of the T65 residue phosphorylation in the CovRD53Amutant cannot derepress therggandspeBtranscription, indicating that phosphorylation at the T65 residue of CovR is not required for repressingrggandspeBtranscription. Furthermore,transcomplementation of the CovRD53Aprotein in the strain that expresses the phosphorylated CovRD53resulted in the repression ofrggandspeBtranscription. Unlike the direct binding of the phosphorylated CovRD53protein and its inhibition ofspeBtranscription demonstrated previously, the present study showed that inactivation of phosphorylation at the D53 residue of CovR contributes dominantly in suppressingrggandspeBtranscription.IMPORTANCECovR/CovS is a two-component regulatory system in group AStreptococcus(GAS). The D53 residue of CovR is phosphorylated by CovS, and the phosphorylated CovRD53binds to thergg-speBintergenic region and acts as the transcriptional repressor. Nonetheless, the transcription ofrggand Rgg-controlledspeBis upregulated in thecovRmutant but inhibited in thecovSmutant. The present study showed that nonphosphorylated CovRD53protein inhibitsrggandspeBtranscription in the presence of the phosphorylated CovRD53in vivo, indicating that nonphosphorylated CovRD53has a dominant role in suppressingrggtranscription. These results reveal the roles of nonphosphorylated CovRD53in regulatingrggtranscription, which could contribute significantly to invasive phenotypes ofcovSmutants.

scholarly journals Conjugation-Mediated Horizontal Gene Transfer of Clostridium perfringens Plasmids in the Chicken Gastrointestinal Tract Results in the Formation of New Virulent Strains

2017 ◽  
Vol 83 (24) ◽  
Author(s):  
Jake A. Lacey ◽  
Anthony L. Keyburn ◽  
Mark E. Ford ◽  
Ricardo W. Portela ◽  
Priscilla A. Johanesen ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Clostridium Perfringens ◽  
Plasmid Transfer ◽  
Conjugative Plasmid ◽  
Conjugative Transfer ◽  
Necrotic Enteritis ◽  
Content Type ◽  
Gastrointestinal Pathogen

ABSTRACT Clostridium perfringens is a gastrointestinal pathogen capable of causing disease in a variety of hosts. Necrotic enteritis in chickens is caused by C. perfringens strains that produce the pore-forming toxin NetB, the major virulence factor for this disease. Like many other C. perfringens toxins and antibiotic resistance genes, NetB is encoded on a conjugative plasmid. Conjugative transfer of the netB-containing plasmid pJIR3535 has been demonstrated in vitro with a netB-null mutant. This study has investigated the effect of plasmid transfer on disease pathogenesis, with two genetically distinct transconjugants constructed under in vitro conditions, within the intestinal tract of chickens. This study also demonstrates that plasmid transfer can occur naturally in the host gut environment without the need for antibiotic selective pressure to be applied. The demonstration of plasmid transfer within the chicken host may have implications for the progression and pathogenesis of C. perfringens-mediated disease. Such horizontal gene transfer events are likely to be common in the clostridia and may be a key factor in strain evolution, both within animals and in the wider environment. IMPORTANCE Clostridium perfringens is a major gastrointestinal pathogen of poultry. C. perfringens strains that express the NetB pore-forming toxin, which is encoded on a conjugative plasmid, cause necrotic enteritis. This study demonstrated that the conjugative transfer of the netB-containing plasmid to two different nonpathogenic strains converted them into disease-causing strains with disease-causing capability similar to that of the donor strain. Plasmid transfer of netB and antibiotic resistance was also demonstrated to occur within the gastrointestinal tract of chickens, with approximately 14% of the isolates recovered comprising three distinct, in vivo-derived, transconjugant types. The demonstration of in vivo plasmid transfer indicates the potential importance of strain plasticity and the contribution of plasmids to strain virulence.

scholarly journals Update on the toxins of Clostridium perfringens and their actions

2017 ◽  
Vol 61 (3) ◽  
pp. 241
Author(s):  
V. S. TSIOURIS (Β.Σ. ΤΣΙΟΥΡΗΣ) ◽  
I. GEORGOPOULOU (ΓΕΩΡΓΟΠΟΥΛΟΥ) ◽  
E. PETRIDOU (Ε. ΠΕΤΡΙΔΟΥ)
Keyword(s):  
Clostridium Perfringens ◽  
Genomic Analysis ◽  
Cytolytic Activity ◽  
Bacterial Toxin ◽  
Necrotic Enteritis ◽  
Alpha Toxin ◽  
The Third ◽  
Epsilon Toxin ◽  
Beta Toxin

Clostridia appeared as a distinct class, approximately 2.7 billion years ago, before the initial formation of oxygen. Clostridium perfringens is widely distributed throughout the environment due to its ability to form spores. Furthermore, it is a member of intestinal microbiota in animals and human. In 2002, the complete genome of C perfringens strain 13 was published. Genomic analysis has revealed that C. perfringens lacks the genetic machinery to produce 13 essential amino acids and it obtains these in vivo via the action of its toxins. Toxins of C perfringens can be divided into major, minor and enterotoxin. C perfringens strains are classified into five toxinotypes (A, B, C, D and E), based on the production of four major toxins. Alpha toxin is the best and most studied major toxin of C perfringens and it was the first bacterial toxin established to possess enzymatic activity. It has haemolytic, necrotic and cytolytic activity, it can lyse platelets and leukocytes and it can damage fibroblasts and muscle cell membranes. Expression of epa gene, which is responsible for the production of alpha toxin by C perfringens, is down-regulated in the normal healthy gut, but it is upregulated to initiate enteric disease in response to an environmental signal. C perfringens appears to be regulated in a quorum sensing manner, using oligopeptides, AI-2 or both, to regulate expression of the epa gene, and thus the synthesis of alpha toxin. Beta toxin is recognized as an important agent in necrotic enteritis of humans and it is the second most lethal C. perfringens toxin following epsilon toxin. Beta toxin is a membrane spanning protein that oligomerizes to form channels in susceptible cells or it primarily acts as a neurotoxin. Epsilon toxin is the most potent of the C. perfringens toxins and the third most potent neurotoxin from the Clostridium spp., following botulinum and tetanus toxins. Epsilon toxin of C perfringens type D causes enterotoxaemia and pulpy kidneys disease of lambs. Iota toxin causes disruption of the actin cytoskeleton and cell barrier integrity and it is the less toxic of the major toxins of C perfringens. Although C perfringens enterotoxin is not classified as one of the major toxins of C perfringens, it is the third most common cause of food poisoning in industrialized nations. It is not secreted by the cells of growing bacteria, but it is released only with the sporulation of C perfringens. Not all strains of C perfringens carry the epe gene, which is responsible for the production of enterotoxin. Theta toxin is a pore-forming cytolysin that can lyse red blood cells. It is produced by all types of C perfringens. Together with alpha-toxin, theta-toxin modulates the host inflammatory response. ß2 toxin is a pore forming toxin which is involved in necrotic enteritis of swine and horse, in haemorragic enteritis of bovine in diarrhea cases of dogs and along with enterotoxin in diarrhea cases of humans. Recently, -NetB, a novel toxin that is associated with broiler necrotic enteritis, has been described. The mechanism of its action seems to involve the formation of small hydrophilic pores. Other toxins of C. perfringens include λ-toxin, ô-toxin, μ-toxin, v-toxin, κ-toxin, a-clostripain like protease and neuraminidase/sialidase. These toxins can act as enzymes, while many of them can act synergically or supplementally with major pore forming toxins. Potentially, C. perfringens might produce more toxins, which have not been identified. Finally, the actions of C. perfringens toxins, major or minor, in some diseases have not been figured out.

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