title: Influence of pCP1NetB ancillary genes on the virulence ofClostridium perfringenspoultry necrotic enteritis strain CP1.
abstract: BACKGROUND
  Necrotic enteritis (NE) is an economically important disease of poultry caused by certainClostridium perfringenstype A strains. The NetB toxin plays a critical role in the pathogenesis of NE. We previously demonstrated thatnetBis located within a 42 kb plasmid-encoded pathogenicity locus (NELoc-1), which also encodes 36 additional genes. Although NetB clearly plays a role in pathogenesis, the involvement of the other NELoc-1 genes has not yet been established. The current study was to provide experimental evidence to confirm the involvement of these genes in NE pathogenesis.
  
  
  RESULTS
  The present study has characterized a virulentC. perfringensstrain (CP1) that has spontaneously lost the NELoc-1-encoding plasmid, pCP1netB. When assessed for cytotoxicity on Leghorn Male Hepatoma (LMH) cells, the culture supernatant of the pCP1netB-deficient CP1 variant (CP1ΔpCP1netB) demonstrated significantly reduced cytotoxicity compared to the wild-type. In addition, CP1ΔpCP1netB was unable to cause intestinal lesions in chickens in a NE disease model. WhennetBalone was introduced into CP1ΔpCP1netB, in vitro cytotoxicity was restored to the wild-type level; however, it did not completely restore virulence when used to challenge broiler chickens [mean lesion score of 0.71 compared to 3.23 in the wild type control group (n = 14)].
  
  
  CONCLUSIONS
  The results of this study suggest that other genes present in NELoc-1, in addition tonetB, are required for full virulence in the chicken challenge model.
authors.affiliation: Beijing Agro-Biotechnology Research Center, Beijing Academy of Agriculture and Forestry Sciences, Beijing, 100097 China.|Guelph Research and Development Centre, Agriculture and Agri-Food Canada, 93 Stone Road West, Guelph, ON N1G 5C9 Canada.
authors.forename: Hongzhuan
authors.initials: H
authors.lastname: Zhou
authors.affiliation: Guelph Research and Development Centre, Agriculture and Agri-Food Canada, 93 Stone Road West, Guelph, ON N1G 5C9 Canada.
authors.forename: Dion
authors.initials: D
authors.lastname: Lepp
authors.affiliation: Department of Pathobiology, University of Guelph, Guelph, ON N1G 2W1 Canada.
authors.forename: Yanlong
authors.initials: Y
authors.lastname: Pei
authors.affiliation: Guelph Research and Development Centre, Agriculture and Agri-Food Canada, 93 Stone Road West, Guelph, ON N1G 5C9 Canada.
authors.forename: Mei
authors.initials: M
authors.lastname: Liu
authors.affiliation: Guelph Research and Development Centre, Agriculture and Agri-Food Canada, 93 Stone Road West, Guelph, ON N1G 5C9 Canada.
authors.forename: Xianhua
authors.initials: X
authors.lastname: Yin
authors.affiliation: Beijing Agro-Biotechnology Research Center, Beijing Academy of Agriculture and Forestry Sciences, Beijing, 100097 China.
authors.forename: Rongcai
authors.initials: R
authors.lastname: Ma
authors.affiliation: Department of Pathobiology, University of Guelph, Guelph, ON N1G 2W1 Canada.
authors.forename: John F
authors.initials: JF
authors.lastname: Prescott
authors.affiliation: Guelph Research and Development Centre, Agriculture and Agri-Food Canada, 93 Stone Road West, Guelph, ON N1G 5C9 Canada.
authors.forename: Joshua
authors.initials: J
authors.lastname: Gong
keywords: Clostridium perfringens; NELoc-1; Necrotic enteritis; NetB; Plasmid-deficient mutant