Prevalence of netB among some clinical isolates of Clostridium perfringens from animals in the United States
ABSTRACT A previously unknown pore forming toxin, called NetB toxin, which is produced by some Australian strains of Clostridium perfringens has recently been reported. This toxin was reported to be critical to the development of the disease necrotic enteritis, in chickens. To investigate the occurrence of the toxin gene (netB) in non-Australian C. perfringens strains, one hundred and six American isolates of C. perfringens were examined. Ninety-two isolates were from chickens, and 14 were from cattle. The netB gene was found in 14 isolates from chickens (7 from chickens with necrotic enteritis, and 7 from unrelated chickens with no evidence of necrotic enteritis). The netB gene was also detected in an isolate recovered from a 3-year-old cow with liver abscesses. The products of all positive netB PCR reactions were sequenced, and these showed 100% nucleotide identity to the netB sequence published in GenBank. Five isolates which had been recovered from five chickens with necrotic enteritis (from four flocks) were netB negative. An additional 24 isolates recovered from one of these lesioned chickens were also netB negative. The present study represents the first study of C. perfringens isolates outside Australia for netB, and the first identification of netB in an isolate from a species other than chickens. The results indicate that the role of NetB in the induction of necrotic enteritis needs to be further investigated, by determining the disease producing capability of both netB positive strains recovered from normal chickens, and netB negative strains recovered from chickens with necrotic enteritis.
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- "ositive strains isolated from animals affected by NE and healthy chickens has been found . However , the per - centage of positive strains in NE isolates was only 53 . 3% and , in addition , even if in low percentage ( 17 . 4% ) , CP that carry NetB gene were isolated also in healthy animals . Our results are in agreement with the data obtained by Martin et al . ( 2009 ) and , though they confirm the involvement of NetB toxin in the pathogenesis of NE , prompt to consid - er that also other pathogenic mechanisms could play an important role on NE appear - ance ."
DESCRIPTION: Diffusion of netB-positive C .perfringens among diseased and healthy chickens in Italy
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- "Existing studies ascertaining the prevalence of netB and tpeL have been limited to certain geographic populations of CP, mainly in Australia, Belgium, Denmark, Sweden, and Canada  . In the United States, studies on the prevalence of these genes have analyzed CP populations from New England, New York, and Pennsylvania . The relatively small number of sampled CP populations underlines a need for more analysis to determine the importance of these genes on a worldwide scale. "
ABSTRACT: Some studies have shown that the NetB toxin may be an important virulence factor of Clostridium perfringens associated necrotic enteritis in poultry. Additionally, research has shown that strains of C. perfringens positive for both the netB gene and a second toxin-encoding gene, tpeL, appear to be more virulent than strains with only netB. In the past, detection of these genes has been performed relatively inefficiently using two single locus PCRs. This report describes a novel multiplex PCR developed to detect netB and tpeL simultaneously in C. perfringens strains isolated from cases of necrotic enteritis in broilers, providing a more efficient diagnostic tool in the screening of strains for these genes.12/2013; 2013:865702. DOI:10.1155/2013/865702
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- "The molecular basis of virulence of C. perfringens associated with NE is still being investigated. However, almost all C. perfringens isolates from cases of NE possess the netB gene    which encodes necrotic enteritis toxin B (NetB), a ␤-pore-forming toxin  . Pore formation by NetB can lead to cell lysis by disruption of membrane integrity and a netB mutant of C. perfringens is reported to be incapable of causing NE . "
ABSTRACT: NetB (necrotic enteritis toxin B) is a recently identified β-pore-forming toxin produced by Clostridium perfringens. This toxin has been shown to play a major role in avian necrotic enteritis. In recent years, a dramatic increase in necrotic enteritis has been observed, especially in countries where the use of antimicrobial growth promoters in animal feedstuffs has been banned. The aim of this work was to determine whether immunisation with a NetB toxoid would provide protection against necrotic enteritis. The immunisation of poultry with a formaldehyde NetB toxoid or with a NetB genetic toxoid (W262A) resulted in the induction of antibody responses against NetB and provided partial protection against disease.Vaccine 05/2013; 31(37). DOI:10.1016/j.vaccine.2013.05.063 · 3.49 Impact Factor