The Experts below are selected from a list of 306 Experts worldwide ranked by ideXlab platform
Horst Posthaus - One of the best experts on this subject based on the ideXlab platform.
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endothelial binding of beta toxin to small intestinal mucosal endothelial cells in early stages of experimentally induced clostridium perfringens type c Enteritis in pigs
Veterinary Pathology, 2013Co-Authors: Vanessa L Schumacher, An Martel, Frank Pasmans, F Van Immerseel, Horst PosthausAbstract:Beta toxin (CPB) is known to be an essential virulence factor in the development of lesions of Clostridium perfringens type C Enteritis in different animal species. Its target cells and exact mechanism of toxicity have not yet been clearly defined. Here, we evaluate the suitability of a neonatal piglet jejunal loop model to investigate early lesions of C. perfringens type C Enteritis. Immunohistochemically, CPB was detected at microvascular endothelial cells in intestinal villi during early and advanced stages of lesions induced by C. perfringens type C. This was first associated with capillary dilatation and subsequently with widespread hemorrhage in affected intestinal segments. CPB was, however, not demonstrated on intestinal epithelial cells. This indicates a tropism of CPB toward endothelial cells and suggests that CPB-induced endothelial damage plays an important role in the early stages of C. perfringens type C Enteritis in pigs.
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susceptibility of primary human endothelial cells to c perfringens beta toxin suggesting similar pathogenesis in human and porcine necrotizing Enteritis
Veterinary Microbiology, 2011Co-Authors: Francesca Popescu, Marianne Wyder, Corinne Gurtner, Andrew R. Greenhill, R A Cooke, Joachim Frey, Horst PosthausAbstract:Clostridium perfringens type C causes fatal necrotizing Enteritis in different mammalian hosts, most commonly in newborn piglets. Human cases are rare, but the disease, also called pigbel, was endemic in the Highlands of Papua New Guinea. Lesions in piglets and humans are very similar and characterized by segmental necro-hemorrhagic Enteritis in acute cases and fibrino-necrotizing Enteritis in subacute cases. Histologically, deep mucosal necrosis accompanied by vascular thrombosis and necrosis was consistently reported in naturally affected pigs and humans. This suggests common pathogenetic mechanisms. Previous in vitro studies using primary porcine aortic endothelial cells suggested that beta-toxin (CPB) induced endothelial damage contributes to the pathogenesis of C. perfringens type C Enteritis in pigs. In the present study we investigated toxic effects of CPB on cultured primary human macro- and microvascular endothelial cells. In vitro, these cells were highly sensitive to CPB and reacted with similar cytopathic and cytotoxic effects as porcine endothelial cells. Our results indicate that porcine and human cell culture based in vitro models represent valuable tools to investigate the pathogenesis of this bacterial disease in animals and humans.
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clostridium perfringens beta toxin targets endothelial cells in necrotizing Enteritis in piglets
Veterinary Microbiology, 2009Co-Authors: Julien Miclard, Marianne Wyder, Benno Grabscheid, E. Sutter, Manu Jaggi, Horst PosthausAbstract:Beta-toxin (CPB) is known to be the major virulence factor of Clostridium perfringens type C strains, which cause necrotizing Enteritis in pigs, sheep, goats, calves, and humans. The exact mode of action, in particular the cellular targets of CPB in the intestine of naturally affected species, is however still not resolved. To investigate localization of CPB in naturally occurring necrotizing Enteritis, we evaluated 52 piglets with spontaneously acquired C. perfringens type C Enteritis and 14 control animals by immunohistochemistry. Our results consistently revealed binding of CPB to vascular endothelial cells in peracute to acute lesions of necrotizing Enteritis. Subacute cases, in contrast, demonstrated reduced or no CPB staining at the endothelium, mainly due to widespread vascular necrosis. From these results we conclude, that the pathogenesis of C. perfringens type C induced necrotizing Enteritis involves binding of CPB to endothelial cells in the small intestine during the early phase of the disease. Thus, by targeting endothelial cells, CPB might specifically induce vascular necrosis, hemorrhage and subsequent hypoxic tissue necrosis.
Robert J. Moore - One of the best experts on this subject based on the ideXlab platform.
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Association between avian necrotic Enteritis and Clostridium perfringens strains expressing NetB toxin
Veterinary Research, 2010Co-Authors: Anthony L. Keyburn, Filip Van Immerseel, Xu-xia Yan, Trudi L. Bannam, Julian I. Rood, Robert J. MooreAbstract:A novel toxin, NetB, has recently been identified in virulent avian Clostridium perfringens isolates and shown to be an essential virulence factor in a clinical necrotic Enteritis isolate. To assess whether NetB is more generally associated with avian necrotic Enteritis isolates we have screened a range of C. perfringens strains from geographically diverse locations for both the presence and expression of the netB gene. Forty-four isolates were derived from necrotic Enteritis disease cases from Australia, Belgium, Denmark and Canada and 55 isolates from healthy chickens from Australia and Belgium. The majority of strains isolated from necrotic Enteritis-affected birds were netB positive (70%) and there was an absolute correlation between the presence of netB and in vitro expression of the NetB protein. Only two of the C. perfringens isolates from healthy chickens carried netB. Sequencing of the netB gene from 23 positive isolates showed that NetB is highly conserved, with only one predicted amino acid (A168T) difference, in six isolates, compared to the published sequence. This change did not alter the in vitro activity of the NetB toxin. The gene encoding the recently discovered TpeL toxin was also screened using PCR and only found in a small proportion of NetB-positive isolates from diseased birds. A selection of NetB-negative isolates, originating from diseased birds, was unable to cause disease in a necrotic Enteritis induction model. This study provides further evidence that NetB is important in pathogenesis and advances our current understanding of C. perfringens virulence factors in avian necrotic Enteritis.
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alpha toxin of clostridium perfringens is not an essential virulence factor in necrotic Enteritis in chickens
Infection and Immunity, 2006Co-Authors: Anthony L. Keyburn, Julian I. Rood, Robert J. Moore, Scott A Sheedy, Mark Ford, Mark M Williamson, Milena M AwadAbstract:The Clostridium perfringens alpha-toxin has previously been implicated as the major virulence factor in necrotic Enteritis in chickens, although definitive proof has not been reported. In this study an alpha-toxin mutant was constructed in a virulent chicken isolate and shown to retain full virulence in a chicken disease model. These results demonstrated that alpha-toxin is not an essential virulence factor in the pathogenesis of necrotic Enteritis in chickens.
Freddy Haesebrouck - One of the best experts on this subject based on the ideXlab platform.
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Rethinking the role of alpha toxin in Clostridium perfringens-associated enteric diseases: a review on bovine necro-haemorrhagic Enteritis
Veterinary Research, 2017Co-Authors: Evy Goossens, Freddy Haesebrouck, Richard Ducatelle, Bonnie R. Valgaeren, Bart Pardon, Piet R. Deprez, Filip Van ImmerseelAbstract:Bovine necro-haemorrhagic Enteritis is an economically important disease caused by Clostridium perfringens type A strains. The disease mainly affects calves under intensive rearing conditions and is characterized by sudden death associated with small intestinal haemorrhage, necrosis and mucosal neutrophil infiltration. The common assumption that, when causing intestinal disease, C. perfringens relies upon specific, plasmid-encoded toxins, was recently challenged by the finding that alpha toxin, which is produced by all C. perfringens strains, is essential for necro-haemorrhagic Enteritis. In addition to alpha toxin, other C. perfringens toxins and/or enzymes might contribute to the pathogenesis of necro-haemorrhagic Enteritis. These additional virulence factors might contribute to breakdown of the protective mucus layer during initial stage of pathogenesis, after which alpha toxin, either or not in synergy with other toxins such as perfringolysin O, can act on the mucosal tissue. Furthermore, alpha toxin alone does not cause intestinal necrosis, indicating that other virulence factors might be needed to cause the extensive tissue necrosis observed in necro-haemorrhagic Enteritis. This review summarizes recent research that has increased our understanding of the pathogenesis of bovine necro-haemorrhagic Enteritis and provides information that is indispensable for the development of novel control strategies, including vaccines.
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the mycotoxin deoxynivalenol predisposes for the development of clostridium perfringens induced necrotic Enteritis in broiler chickens
PLOS ONE, 2014Co-Authors: Gunther Antonissen, Leen Timbermont, Frank Pasmans, Freddy Haesebrouck, Richard Ducatelle, Filip Van Immerseel, Marc Verlinden, Geert Janssens, Venessa Eeckhaut, Mia EeckhoutAbstract:Both mycotoxin contamination of feed and Clostridium perfringens-induced necrotic Enteritis have an increasing global economic impact on poultry production. Especially the Fusarium mycotoxin deoxynivalenol (DON) is a common feed contaminant. This study aimed at examining the predisposing effect of DON on the development of necrotic Enteritis in broiler chickens. An experimental Clostridium perfringens infection study revealed that DON, at a contamination level of 3,000 to 4,000 mg/kg feed, increased the percentage of birds with subclinical necrotic Enteritis from 2062.6% to 4763.0% (P,0.001). DON significantly reduced the transepithelial electrical resistance in duodenal segments (P,0.001) and decreased duodenal villus height (P=0.014) indicating intestinal barrier disruption and intestinal epithelial damage, respectively. This may lead to an increased permeability of the intestinal epithelium and decreased absorption of dietary proteins. Protein analysis of duodenal content indeed showed that DON contamination resulted in a significant increase in total protein concentration (P=0.023). Furthermore, DON had no effect on in vitro growth, alpha toxin production and netB toxin transcription of Clostridium perfringens. In conclusion, feed contamination with DON at concentrations below the European maximum guidance level of 5,000 mg/kg feed, is a predisposing factor for the development of necrotic Enteritis in broilers. These results are associated with a negative effect of DON on the intestinal barrier function and increased intestinal protein availability, which may stimulate growth and toxin production of Clostridium perfringens.
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The synergistic necrohemorrhagic action of Clostridium perfringens perfringolysin and alpha toxin in the bovine intestine and against bovine endothelial cells
Veterinary Research, 2013Co-Authors: Stefanie Verherstraeten, Leen Timbermont, Freddy Haesebrouck, Richard Ducatelle, Evy Goossens, Bart Pardon, Bonnie Valgaeren, Karen Vermeulen, Stijn Schauvliege, Piet DeprezAbstract:Bovine necrohemorrhagic Enteritis is a major cause of mortality in veal calves. Clostridium perfringens is considered as the causative agent, but there has been controversy on the toxins responsible for the disease. Recently, it has been demonstrated that a variety of C . perfringens type A strains can induce necrohemorrhagic lesions in a calf intestinal loop assay. These results put forward alpha toxin and perfringolysin as potential causative toxins, since both are produced by all C . perfringens type A strains. The importance of perfringolysin in the pathogenesis of bovine necrohemorrhagic Enteritis has not been studied before. Therefore, the objective of the current study was to evaluate the role of perfringolysin in the development of necrohemorrhagic Enteritis lesions in calves and its synergism with alpha toxin. A perfringolysin-deficient mutant, an alpha toxin-deficient mutant and a perfringolysin alpha toxin double mutant were less able to induce necrosis in a calf intestinal loop assay as compared to the wild-type strain. Only complementation with both toxins could restore the activity to that of the wild-type. In addition, perfringolysin and alpha toxin had a synergistic cytotoxic effect on bovine endothelial cells. This endothelial cell damage potentially explains why capillary hemorrhages are an initial step in the development of bovine necrohemorrhagic Enteritis. Taken together, our results show that perfringolysin acts synergistically with alpha toxin in the development of necrohemorrhagic Enteritis in a calf intestinal loop model and we hypothesize that both toxins act by targeting the endothelial cells.
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necrotic Enteritis in broilers an updated review on the pathogenesis
Avian Pathology, 2011Co-Authors: Leen Timbermont, Freddy Haesebrouck, Richard Ducatelle, F Van ImmerseelAbstract:Clostridium perfringens-induced necrotic Enteritis and related subclinical disease have become economically significant problems for the broiler industry. Fortunately, scientific interest in this topic has grown: new C. perfringens virulence factors have been discovered and new insight gained about the pathogenesis of necrotic Enteritis. It has been shown that alpha toxin, for a long time thought to be the key virulence factor, is not essential for the development of the disease. Moreover, it is now clearly established that only certain C. perfringens strains are capable of inducing necrotic Enteritis under specific conditions that predispose to the disease and they constitute only a minority in the intestinal tract of healthy chickens. A novel pore-forming toxin, NetB, has been identified in these virulent avian C. perfringens strains. Using a gene knockout mutant, it has been shown that NetB is a critical virulence factor in the pathogenesis of necrotic Enteritis in broilers. In addition to toxin production, other factors have been described that contribute to the ability of certain C. perfringens strains to cause necrotic Enteritis in broilers. It has been suggested that proteolytic enzymes play an important role in the initial stages of necrotic Enteritis since the villi are first affected at the level of the basement membrane and the lateral domain of the enterocytes. In field outbreaks of necrotic Enteritis, a single clone of C. perfringens is dominant in intestines of all affected birds, as opposed to the mixture of different C. perfringens strains that can be isolated from healthy bird intestines. It has been proposed that bacteriocin production is responsible for the dominance of a single strain in necrotic Enteritis cases. Furthermore, it has been shown that virulent strains are more able to adhere to extracellular matrix molecules than non-virulent strains. The current knowledge on the pathogenesis of the disease has been summarized in this short review.
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origin of clostridium perfringens isolates determines the ability to induce necrotic Enteritis in broilers
Comparative Immunology Microbiology and Infectious Diseases, 2009Co-Authors: Leen Timbermont, Anouk Lanckriet, Ahmadreeza Gholamiandehkordi, Frank Pasmans, An Martel, Freddy Haesebrouck, Richard Ducatelle, Filip Van ImmerseelAbstract:Since the ban on growth-promoting antibiotics in animal feed in the European Union, necrotic Enteritis has become a major cause of mortality in broiler chickens. Despite the importance of the disease, the pathogenesis is still not completely understood. In the current study, Clostridium perfringens strains isolated from healthy flocks and isolates from outbreaks of necrotic Enteritis were evaluated for the ability to cause gut necrosis in an intestinal loop model in laying hens and in an experimental infection model in broilers. High, intermediate and low alpha toxin producing strains were chosen from each isolation source. Only the isolates from field outbreaks induced necrotic gut lesions, independent of the amount of alpha toxin produced in vitro. It was also shown that alpha toxin producing isolates from calf hemorrhagic Enteritis cases were not able to induce necrotic Enteritis in poultry. These results suggest the presence of host specific virulence factors in C. perfringens strains, isolated from chickens with intestinal necrotic Enteritis lesions.
Richard Ducatelle - One of the best experts on this subject based on the ideXlab platform.
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Rethinking the role of alpha toxin in Clostridium perfringens-associated enteric diseases: a review on bovine necro-haemorrhagic Enteritis
Veterinary Research, 2017Co-Authors: Evy Goossens, Freddy Haesebrouck, Richard Ducatelle, Bonnie R. Valgaeren, Bart Pardon, Piet R. Deprez, Filip Van ImmerseelAbstract:Bovine necro-haemorrhagic Enteritis is an economically important disease caused by Clostridium perfringens type A strains. The disease mainly affects calves under intensive rearing conditions and is characterized by sudden death associated with small intestinal haemorrhage, necrosis and mucosal neutrophil infiltration. The common assumption that, when causing intestinal disease, C. perfringens relies upon specific, plasmid-encoded toxins, was recently challenged by the finding that alpha toxin, which is produced by all C. perfringens strains, is essential for necro-haemorrhagic Enteritis. In addition to alpha toxin, other C. perfringens toxins and/or enzymes might contribute to the pathogenesis of necro-haemorrhagic Enteritis. These additional virulence factors might contribute to breakdown of the protective mucus layer during initial stage of pathogenesis, after which alpha toxin, either or not in synergy with other toxins such as perfringolysin O, can act on the mucosal tissue. Furthermore, alpha toxin alone does not cause intestinal necrosis, indicating that other virulence factors might be needed to cause the extensive tissue necrosis observed in necro-haemorrhagic Enteritis. This review summarizes recent research that has increased our understanding of the pathogenesis of bovine necro-haemorrhagic Enteritis and provides information that is indispensable for the development of novel control strategies, including vaccines.
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the mycotoxin deoxynivalenol predisposes for the development of clostridium perfringens induced necrotic Enteritis in broiler chickens
PLOS ONE, 2014Co-Authors: Gunther Antonissen, Leen Timbermont, Frank Pasmans, Freddy Haesebrouck, Richard Ducatelle, Filip Van Immerseel, Marc Verlinden, Geert Janssens, Venessa Eeckhaut, Mia EeckhoutAbstract:Both mycotoxin contamination of feed and Clostridium perfringens-induced necrotic Enteritis have an increasing global economic impact on poultry production. Especially the Fusarium mycotoxin deoxynivalenol (DON) is a common feed contaminant. This study aimed at examining the predisposing effect of DON on the development of necrotic Enteritis in broiler chickens. An experimental Clostridium perfringens infection study revealed that DON, at a contamination level of 3,000 to 4,000 mg/kg feed, increased the percentage of birds with subclinical necrotic Enteritis from 2062.6% to 4763.0% (P,0.001). DON significantly reduced the transepithelial electrical resistance in duodenal segments (P,0.001) and decreased duodenal villus height (P=0.014) indicating intestinal barrier disruption and intestinal epithelial damage, respectively. This may lead to an increased permeability of the intestinal epithelium and decreased absorption of dietary proteins. Protein analysis of duodenal content indeed showed that DON contamination resulted in a significant increase in total protein concentration (P=0.023). Furthermore, DON had no effect on in vitro growth, alpha toxin production and netB toxin transcription of Clostridium perfringens. In conclusion, feed contamination with DON at concentrations below the European maximum guidance level of 5,000 mg/kg feed, is a predisposing factor for the development of necrotic Enteritis in broilers. These results are associated with a negative effect of DON on the intestinal barrier function and increased intestinal protein availability, which may stimulate growth and toxin production of Clostridium perfringens.
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The synergistic necrohemorrhagic action of Clostridium perfringens perfringolysin and alpha toxin in the bovine intestine and against bovine endothelial cells
Veterinary Research, 2013Co-Authors: Stefanie Verherstraeten, Leen Timbermont, Freddy Haesebrouck, Richard Ducatelle, Evy Goossens, Bart Pardon, Bonnie Valgaeren, Karen Vermeulen, Stijn Schauvliege, Piet DeprezAbstract:Bovine necrohemorrhagic Enteritis is a major cause of mortality in veal calves. Clostridium perfringens is considered as the causative agent, but there has been controversy on the toxins responsible for the disease. Recently, it has been demonstrated that a variety of C . perfringens type A strains can induce necrohemorrhagic lesions in a calf intestinal loop assay. These results put forward alpha toxin and perfringolysin as potential causative toxins, since both are produced by all C . perfringens type A strains. The importance of perfringolysin in the pathogenesis of bovine necrohemorrhagic Enteritis has not been studied before. Therefore, the objective of the current study was to evaluate the role of perfringolysin in the development of necrohemorrhagic Enteritis lesions in calves and its synergism with alpha toxin. A perfringolysin-deficient mutant, an alpha toxin-deficient mutant and a perfringolysin alpha toxin double mutant were less able to induce necrosis in a calf intestinal loop assay as compared to the wild-type strain. Only complementation with both toxins could restore the activity to that of the wild-type. In addition, perfringolysin and alpha toxin had a synergistic cytotoxic effect on bovine endothelial cells. This endothelial cell damage potentially explains why capillary hemorrhages are an initial step in the development of bovine necrohemorrhagic Enteritis. Taken together, our results show that perfringolysin acts synergistically with alpha toxin in the development of necrohemorrhagic Enteritis in a calf intestinal loop model and we hypothesize that both toxins act by targeting the endothelial cells.
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necrotic Enteritis in broilers an updated review on the pathogenesis
Avian Pathology, 2011Co-Authors: Leen Timbermont, Freddy Haesebrouck, Richard Ducatelle, F Van ImmerseelAbstract:Clostridium perfringens-induced necrotic Enteritis and related subclinical disease have become economically significant problems for the broiler industry. Fortunately, scientific interest in this topic has grown: new C. perfringens virulence factors have been discovered and new insight gained about the pathogenesis of necrotic Enteritis. It has been shown that alpha toxin, for a long time thought to be the key virulence factor, is not essential for the development of the disease. Moreover, it is now clearly established that only certain C. perfringens strains are capable of inducing necrotic Enteritis under specific conditions that predispose to the disease and they constitute only a minority in the intestinal tract of healthy chickens. A novel pore-forming toxin, NetB, has been identified in these virulent avian C. perfringens strains. Using a gene knockout mutant, it has been shown that NetB is a critical virulence factor in the pathogenesis of necrotic Enteritis in broilers. In addition to toxin production, other factors have been described that contribute to the ability of certain C. perfringens strains to cause necrotic Enteritis in broilers. It has been suggested that proteolytic enzymes play an important role in the initial stages of necrotic Enteritis since the villi are first affected at the level of the basement membrane and the lateral domain of the enterocytes. In field outbreaks of necrotic Enteritis, a single clone of C. perfringens is dominant in intestines of all affected birds, as opposed to the mixture of different C. perfringens strains that can be isolated from healthy bird intestines. It has been proposed that bacteriocin production is responsible for the dominance of a single strain in necrotic Enteritis cases. Furthermore, it has been shown that virulent strains are more able to adhere to extracellular matrix molecules than non-virulent strains. The current knowledge on the pathogenesis of the disease has been summarized in this short review.
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origin of clostridium perfringens isolates determines the ability to induce necrotic Enteritis in broilers
Comparative Immunology Microbiology and Infectious Diseases, 2009Co-Authors: Leen Timbermont, Anouk Lanckriet, Ahmadreeza Gholamiandehkordi, Frank Pasmans, An Martel, Freddy Haesebrouck, Richard Ducatelle, Filip Van ImmerseelAbstract:Since the ban on growth-promoting antibiotics in animal feed in the European Union, necrotic Enteritis has become a major cause of mortality in broiler chickens. Despite the importance of the disease, the pathogenesis is still not completely understood. In the current study, Clostridium perfringens strains isolated from healthy flocks and isolates from outbreaks of necrotic Enteritis were evaluated for the ability to cause gut necrosis in an intestinal loop model in laying hens and in an experimental infection model in broilers. High, intermediate and low alpha toxin producing strains were chosen from each isolation source. Only the isolates from field outbreaks induced necrotic gut lesions, independent of the amount of alpha toxin produced in vitro. It was also shown that alpha toxin producing isolates from calf hemorrhagic Enteritis cases were not able to induce necrotic Enteritis in poultry. These results suggest the presence of host specific virulence factors in C. perfringens strains, isolated from chickens with intestinal necrotic Enteritis lesions.
Filip Van Immerseel - One of the best experts on this subject based on the ideXlab platform.
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variable protection against experimental broiler necrotic Enteritis after immunization with the c terminal fragment of clostridium perfringens alpha toxin and a non toxic netb variant
Avian Pathology, 2016Co-Authors: Sergio Fernandes P Da Costa, Filip Van Immerseel, Dorien Mot, Sofie Geeraerts, Monika Bokoribrown, Richard W TitballAbstract:Necrotic Enteritis toxin B (NetB) is a pore-forming toxin produced by Clostridium perfringens and has been shown to play a key role in avian necrotic Enteritis, a disease causing significant costs to the poultry production industry worldwide. The aim of this work was to determine whether immunization with a non-toxic variant of NetB (NetB W262A) and the C-terminal fragment of C. perfringens alpha-toxin (CPA247-370) would provide protection against experimental necrotic Enteritis. Immunized birds with either antigen or a combination of antigens developed serum antibody levels against NetB and CPA. When CPA247-370 and NetB W262A were used in combination as immunogens, an increased protection was observed after oral challenge by individual dosing, but not after in-feed-challenge.
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the mycotoxin deoxynivalenol predisposes for the development of clostridium perfringens induced necrotic Enteritis in broiler chickens
PLOS ONE, 2014Co-Authors: Gunther Antonissen, Leen Timbermont, Frank Pasmans, Freddy Haesebrouck, Richard Ducatelle, Filip Van Immerseel, Marc Verlinden, Geert Janssens, Venessa Eeckhaut, Mia EeckhoutAbstract:Both mycotoxin contamination of feed and Clostridium perfringens-induced necrotic Enteritis have an increasing global economic impact on poultry production. Especially the Fusarium mycotoxin deoxynivalenol (DON) is a common feed contaminant. This study aimed at examining the predisposing effect of DON on the development of necrotic Enteritis in broiler chickens. An experimental Clostridium perfringens infection study revealed that DON, at a contamination level of 3,000 to 4,000 mg/kg feed, increased the percentage of birds with subclinical necrotic Enteritis from 2062.6% to 4763.0% (P,0.001). DON significantly reduced the transepithelial electrical resistance in duodenal segments (P,0.001) and decreased duodenal villus height (P=0.014) indicating intestinal barrier disruption and intestinal epithelial damage, respectively. This may lead to an increased permeability of the intestinal epithelium and decreased absorption of dietary proteins. Protein analysis of duodenal content indeed showed that DON contamination resulted in a significant increase in total protein concentration (P=0.023). Furthermore, DON had no effect on in vitro growth, alpha toxin production and netB toxin transcription of Clostridium perfringens. In conclusion, feed contamination with DON at concentrations below the European maximum guidance level of 5,000 mg/kg feed, is a predisposing factor for the development of necrotic Enteritis in broilers. These results are associated with a negative effect of DON on the intestinal barrier function and increased intestinal protein availability, which may stimulate growth and toxin production of Clostridium perfringens.
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Association between avian necrotic Enteritis and Clostridium perfringens strains expressing NetB toxin
Veterinary Research, 2010Co-Authors: Anthony L. Keyburn, Filip Van Immerseel, Xu-xia Yan, Trudi L. Bannam, Julian I. Rood, Robert J. MooreAbstract:A novel toxin, NetB, has recently been identified in virulent avian Clostridium perfringens isolates and shown to be an essential virulence factor in a clinical necrotic Enteritis isolate. To assess whether NetB is more generally associated with avian necrotic Enteritis isolates we have screened a range of C. perfringens strains from geographically diverse locations for both the presence and expression of the netB gene. Forty-four isolates were derived from necrotic Enteritis disease cases from Australia, Belgium, Denmark and Canada and 55 isolates from healthy chickens from Australia and Belgium. The majority of strains isolated from necrotic Enteritis-affected birds were netB positive (70%) and there was an absolute correlation between the presence of netB and in vitro expression of the NetB protein. Only two of the C. perfringens isolates from healthy chickens carried netB. Sequencing of the netB gene from 23 positive isolates showed that NetB is highly conserved, with only one predicted amino acid (A168T) difference, in six isolates, compared to the published sequence. This change did not alter the in vitro activity of the NetB toxin. The gene encoding the recently discovered TpeL toxin was also screened using PCR and only found in a small proportion of NetB-positive isolates from diseased birds. A selection of NetB-negative isolates, originating from diseased birds, was unable to cause disease in a necrotic Enteritis induction model. This study provides further evidence that NetB is important in pathogenesis and advances our current understanding of C. perfringens virulence factors in avian necrotic Enteritis.
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origin of clostridium perfringens isolates determines the ability to induce necrotic Enteritis in broilers
Comparative Immunology Microbiology and Infectious Diseases, 2009Co-Authors: Leen Timbermont, Anouk Lanckriet, Ahmadreeza Gholamiandehkordi, Frank Pasmans, An Martel, Freddy Haesebrouck, Richard Ducatelle, Filip Van ImmerseelAbstract:Since the ban on growth-promoting antibiotics in animal feed in the European Union, necrotic Enteritis has become a major cause of mortality in broiler chickens. Despite the importance of the disease, the pathogenesis is still not completely understood. In the current study, Clostridium perfringens strains isolated from healthy flocks and isolates from outbreaks of necrotic Enteritis were evaluated for the ability to cause gut necrosis in an intestinal loop model in laying hens and in an experimental infection model in broilers. High, intermediate and low alpha toxin producing strains were chosen from each isolation source. Only the isolates from field outbreaks induced necrotic gut lesions, independent of the amount of alpha toxin produced in vitro. It was also shown that alpha toxin producing isolates from calf hemorrhagic Enteritis cases were not able to induce necrotic Enteritis in poultry. These results suggest the presence of host specific virulence factors in C. perfringens strains, isolated from chickens with intestinal necrotic Enteritis lesions.