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Infection and Immunity, April 2007, p. 1811-1819, Vol. 75, No. 4
0019-9567/07/$08.00+0     doi:10.1128/IAI.01981-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Comparison of Virulence Plasmids among Clostridium perfringens Type E Isolates{triangledown} ,{dagger}

Jihong Li,1 Kazuaki Miyamoto,2 and Bruce A. McClane1,3*

Department of Molecular Genetics and Biochemistry, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261,1 Department of Microbiology, Wakayama University School of Medicine, 811-1 Kimiidera, Wakayama, 641-0012, Japan,2 Australian Research Council Centre of Excellence in Structural and Functional Microbial Genomics, Monash University, Victoria, Australia3

Received 18 December 2006/ Returned for modification 8 January 2007/ Accepted 16 January 2007

Clostridium perfringens type E isolates produce iota-toxin, which is encoded by iap and ibp genes. Using Southern blot analyses, the current study identified iap/ibp plasmids of ~97 or ~135 kb among eight type E isolates. For most of these isolates, their iap/ibp plasmid also encoded urease and lambda-toxin. However, the beta2-toxin gene, if present, was on a different plasmid from the iap/ibp plasmid. For all isolates, the iap/ibp plasmid carried a tcp locus, strongly suggesting that these plasmids are conjugative. Overlapping PCR analyses demonstrated some similarity between the iap/ibp plasmids and enterotoxin-encoding plasmids of type A isolates. Additional PCR analyses demonstrated that the iap/ibp locus is located near dcm sequences, an apparent plasmid hot spot for toxin gene insertion, and that two IS1151-related sequences are present in the iap/ibp locus. To begin testing whether those IS1151-like sequences can mobilize iap/ibp genes, a PCR assay was performed that amplifies a product only from circular DNA forms that could represent transposition intermediates. This PCR assay detected circular forms containing iap/ibp genes and silent enterotoxin gene sequences, with or without an IS1151-like sequence. Collectively, these results suggest that a mobile genetic element carrying iap/ibp has inserted onto a tcp-carrying enterotoxin plasmid in a type A isolate, creating a progenitor iap/ibp plasmid. That plasmid then spread via conjugation to other isolates, converting them to type E. Further iap/ibp plasmid diversity occurred when either the iap/ibp genes later remobilized and inserted onto other conjugative plasmids or some iap/ibp plasmids acquired additional DNA sequences.

* Corresponding author. Mailing address: E1240 BST, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261. Phone: (412) 648-9022. Fax: (412) 624-1401. E-mail: bamcc{at}pitt.edu.

{triangledown} Published ahead of print on 29 January 2007.

Editor: D. L. Burns

{dagger} Supplemental material for this article may be found at http://iai.asm.org/.

Infection and Immunity, April 2007, p. 1811-1819, Vol. 75, No. 4
0019-9567/07/$08.00+0     doi:10.1128/IAI.01981-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Miyamoto, K., Li, J., Sayeed, S., Akimoto, S., McClane, B. A. (2008). Sequencing and Diversity Analyses Reveal Extensive Similarities between Some Epsilon-Toxin-Encoding Plasmids and the pCPF5603 Clostridium perfringens Enterotoxin Plasmid. J. Bacteriol. 190: 7178-7188 [Abstract] [Full Text]  
  • Parsons, J. A., Bannam, T. L., Devenish, R. J., Rood, J. I. (2007). TcpA, an FtsK/SpoIIIE Homolog, Is Essential for Transfer of the Conjugative Plasmid pCW3 in Clostridium perfringens. J. Bacteriol. 189: 7782-7790 [Abstract] [Full Text]  


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