DNA Sequence of a ColV Plasmid and Prevalence of Selected Plasmid-Encoded Virulence Genes among Avian <i>Escherichia coli</i> Strains

DOI Web Site 2 Citations
  • Timothy J. Johnson
    Department of Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, 1802 Elwood Drive, VMRI #2, Iowa State University, Ames, Iowa 50011
  • Kylie E. Siek
    Department of Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, 1802 Elwood Drive, VMRI #2, Iowa State University, Ames, Iowa 50011
  • Sara J. Johnson
    Department of Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, 1802 Elwood Drive, VMRI #2, Iowa State University, Ames, Iowa 50011
  • Lisa K. Nolan
    Department of Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, 1802 Elwood Drive, VMRI #2, Iowa State University, Ames, Iowa 50011

Abstract

<jats:title>ABSTRACT</jats:title> <jats:p> ColV plasmids have long been associated with the virulence of <jats:italic>Escherichia coli</jats:italic> , despite the fact that their namesake trait, ColV production, does not appear to contribute to virulence. Such plasmids or their associated sequences appear to be quite common among avian pathogenic <jats:italic>E. coli</jats:italic> (APEC) and are strongly linked to the virulence of these organisms. In the present study, a 180-kb ColV plasmid was sequenced and analyzed. This plasmid, pAPEC-O2-ColV, possesses a 93-kb region containing several putative virulence traits, including <jats:italic>iss</jats:italic> , <jats:italic>tsh</jats:italic> , and four putative iron acquisition and transport systems. The iron acquisition and transport systems include those encoding aerobactin and salmochelin, the <jats:italic>sit</jats:italic> ABC iron transport system, and a putative iron transport system novel to APEC, <jats:italic>eit</jats:italic> . In order to determine the prevalence of the virulence-associated genes within this region among avian <jats:italic>E. coli</jats:italic> strains, 595 APEC and 199 avian commensal <jats:italic>E. coli</jats:italic> isolates were examined for genes of this region using PCR. Results indicate that genes contained within a portion of this putative virulence region are highly conserved among APEC and that the genes of this region occur significantly more often in APEC than in avian commensal <jats:italic>E. coli</jats:italic> . The region of pAPEC-O2-ColV containing genes that are highly prevalent among APEC appears to be a distinguishing trait of APEC strains. </jats:p>

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