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The Citrobacter rodentium Mouse Model: Studying Pathogen and Host Contributions to Infectious Colitis
11:04

The Citrobacter rodentium Mouse Model: Studying Pathogen and Host Contributions to Infectious Colitis

Published on: February 19, 2013

The Citrobacter rodentium genome sequence reveals convergent evolution with human pathogenic Escherichia coli

Nicola K Petty1, Richard Bulgin, Valerie F Crepin

  • 1The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA, UK.

Journal of Bacteriology
|November 10, 2009
PubMed

Insights

Citrobacter rodentium, a mouse pathogen, shares virulence strategies with E. coli via a type III secretion system (T3SS). Genome sequencing reveals specific genes and novel effectors, suggesting convergent evolution in host infection.

Area of Science:

  • Microbiology
  • Genomics
  • Pathogen Biology

Background:

  • Citrobacter rodentium causes colitis in mice, employing a type III secretion system (T3SS) for virulence, similar to EPEC and EHEC.
  • Understanding C. rodentium's genomic makeup is crucial for elucidating its pathogenic mechanisms and evolutionary history.

Purpose of the Study:

  • To fully annotate the genome sequence of Citrobacter rodentium strain ICC168.
  • To identify specific genes, genomic islands, and secretion systems involved in C. rodentium's virulence.
  • To compare C. rodentium's genetic content with related pathogens like EPEC and EHEC.

Main Methods:

  • Whole-genome sequencing of C. rodentium strain ICC168.
  • Bioinformatic analysis for gene identification, including specific coding sequences, prophage regions, and genomic islands.
  • Comparative genomics to identify orthologues and unique genetic elements compared to EPEC and EHEC.

Main Results:

  • The 5.3-Mb chromosome and four plasmids of C. rodentium ICC168 were fully sequenced and annotated.
  • 1,585 C. rodentium-specific coding sequences, 10 prophage-like regions, and 17 genomic islands, including the locus for enterocyte effacement (LEE), were identified.
  • C. rodentium possesses 29 T3SS effectors, including all 22 core effectors of EPEC, and a novel effector, EspS. It also has two type VI secretion systems (T6SS), CTS1 and CTS2.

Conclusions:

  • C. rodentium and EPEC/EHEC exhibit convergent evolution in host infection strategies, likely due to shared mobile DNA.
  • The genome sequence provides insights into C. rodentium's phylogenetic position and adaptation.
  • C. rodentium may have lost gene functions related to a prior pathogenic niche, indicating evolutionary plasticity.

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