Characterization of virulence plasmid diversity among Clostridium perfringens type B isolates.
The important veterinary pathogen Clostridium perfringens type B is unique for producing the two most lethal C. perfringens toxins, i.e., epsilon-toxin and beta-toxin. Our recent study (K. Miyamoto, J. Li, S. Sayeed, S. Akimoto, and B. A. McClane, J. Bacteriol. 190:7178-7188, 2008) showed that most, if not all, type B isolates carry a 65-kb epsilon-toxin-encoding plasmid. However, this epsilon-toxin plasmid did not possess the cpb gene encoding beta-toxin, suggesting that type B isolates carry at least one additional virulence plasmid. Therefore, the current study used Southern blotting of pulsed-field gels to localize the cpb gene to approximately 90-kb plasmids in most type B isolates, although a few isolates carried a approximately 65-kb cpb plasmid distinct from their etx plasmid. Overlapping PCR analysis then showed that the gene encoding the recently discovered TpeL toxin is located approximately 3 kb downstream of the plasmid-borne cpb gene. As shown earlier for their epsilon-toxin-encoding plasmids, the beta-toxin-encoding plasmids of type B isolates were found to carry a tcp locus, suggesting that they are conjugative. Additionally, IS1151-like sequences were identified upstream of the cpb gene in type B isolates. These IS1151-like sequences may mobilize the cpb gene based upon detection of possible cpb-containing circular transposition intermediates. Most type B isolates also possessed a third virulence plasmid that carries genes encoding urease and lambda-toxin. Collectively, these findings suggest that type B isolates are among the most plasmid dependent of all C. perfringens isolates for virulence, as they usually carry three potential virulence plasmids.
Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA.
Sameera
S
Sayeed
Jihong
J
Li
Bruce A
BA
McClane
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001427:Bacterial Toxins / Q000235:genetics* / Q000378:metabolism*; D003016:Clostridium perfringens / Q000145:classification* / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D014644:Genetic Variation; D010957:Plasmids / Q000235:genetics*; D014774:Virulence
D001426:Bacterial Proteins; D001427:Bacterial Toxins