Martin Thomas G, Smyth Joan A
Department of Pathobiology and Veterinary Science, University of Connecticut, Storrs, CT 06269, USA.
Vet Microbiol. 2009 Apr 14;136(1-2):202-5. doi: 10.1016/j.vetmic.2008.10.026. Epub 2008 Oct 31.
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.
最近有报道称，一些澳大利亚产气荚膜梭菌菌株会产生一种以前未知的成孔毒素，即NetB毒素。据报道，这种毒素对鸡坏死性肠炎的发病至关重要。为了调查非澳大利亚产气荚膜梭菌菌株中毒素基因（netB）的出现情况，对106株美国产气荚膜梭菌分离株进行了检测。其中92株分离株来自鸡，14株来自牛。在14株来自鸡的分离株中发现了netB基因（7株来自患有坏死性肠炎的鸡，7株来自无坏死性肠炎迹象的无关鸡）。在从一头患有肝脓肿的3岁奶牛身上分离出的一株菌株中也检测到了netB基因。对所有netB PCR阳性反应产物进行了测序，结果显示其与GenBank中公布的netB序列具有100%的核苷酸同一性。从五只患有坏死性肠炎的鸡（来自四个鸡群）中分离出的五株菌株netB呈阴性。从其中一只患病鸡身上另外分离出的24株菌株netB也呈阴性。本研究是对澳大利亚以外产气荚膜梭菌分离株进行的首次netB研究，也是首次在鸡以外的物种分离株中鉴定出netB。结果表明，需要通过测定从正常鸡中分离出的netB阳性菌株和从患有坏死性肠炎的鸡中分离出的netB阴性菌株的致病能力，进一步研究NetB在坏死性肠炎诱导中的作用。
