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Enrichment and Detection of Clostridium perfringens Toxinotypes in Retail Food Samples
Published on: October 18, 2019
Comparison of virulence plasmids among Clostridium perfringens type E isolates
Jihong Li1, Kazuaki Miyamoto, Bruce A McClane
1Department of Molecular Genetics and Biochemistry, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA.
Infection and Immunity
|January 31, 2007
Summary
Clostridium perfringens type E isolates harbor iota-toxin genes on large plasmids. These plasmids likely originated from mobile genetic elements inserting into existing plasmids, which then spread through conjugation, leading to type E strains.
Area of Science:
- Microbiology
- Genetics
- Molecular Biology
Background:
- Clostridium perfringens type E produces iota-toxin, encoded by iap and ibp genes.
- Understanding the genetic basis of toxin production in C. perfringens is crucial for disease control.
Purpose of the Study:
- To characterize the plasmids carrying iota-toxin genes (iap/ibp) in Clostridium perfringens type E isolates.
- To investigate the origin and spread of these iota-toxin encoding plasmids.
Main Methods:
- Southern blot analysis to identify plasmid sizes.
- Polymerase Chain Reaction (PCR) to detect toxin genes, plasmid loci, and mobile genetic elements.
- Analysis of plasmid similarities and potential mobilization mechanisms.
Main Results:
- Identified iap/ibp plasmids of ~97 or ~135 kb in type E isolates.
- Most iap/ibp plasmids also carried urease and lambda-toxin genes, with beta2-toxin on separate plasmids.
- Evidence suggests iap/ibp genes mobilized via IS1151-related sequences and inserted onto conjugative plasmids, potentially originating from type A strains.
- Detected circular DNA forms indicating transposition intermediates of iap/ibp genes.
Conclusions:
- The iota-toxin encoding plasmids in C. perfringens type E likely arose from the insertion of a mobile genetic element into a conjugative plasmid, possibly in a type A strain.
- Conjugative transfer of these modified plasmids led to the emergence and spread of type E strains.
- Plasmid diversity is further generated through remobilization and acquisition of additional DNA sequences.
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