title: The Dynamics of Genetic Interactions between Vibrio metoecus and Vibrio cholerae, Two Close Relatives Co-Occurring in the Environment.
abstract: Vibrio metoecus is the closest relative of Vibrio cholerae, the causative agent of the potent diarrheal disease cholera. Although the pathogenic potential of this new species is yet to be studied in depth, it has been co-isolated with V. cholerae in coastal waters and found in clinical specimens in the United States. We used these two organisms to investigate the genetic interaction between closely related species in their natural environment. The genomes of 20 V. cholerae and 4 V. metoecus strains isolated from a brackish coastal pond on the US east coast, as well as 4 clinical V. metoecus strains were sequenced and compared with reference strains. Whole genome comparison shows 86-87% average nucleotide identity (ANI) in their core genes between the two species. On the other hand, the chromosomal integron, which occupies approximately 3% of their genomes, shows higher conservation in ANI between species than any other region of their genomes. The ANI of 93-94% observed in this region is not significantly greater within than between species, meaning that it does not follow species boundaries. Vibrio metoecus does not encode toxigenic V. cholerae major virulence factors, the cholera toxin and toxin-coregulated pilus. However, some of the pathogenicity islands found in pandemic V. cholerae were either present in the common ancestor it shares with V. metoecus, or acquired by clinical and environmental V. metoecus in partial fragments. The virulence factors of V. cholerae are therefore both more ancient and more widespread than previously believed. There is high interspecies recombination in the core genome, which has been detected in 24% of the single-copy core genes, including genes involved in pathogenicity. Vibrio metoecus was six times more often the recipient of DNA from V. cholerae as it was the donor, indicating a strong bias in the direction of gene transfer in the environment.
authors.affiliation: Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Fabini D
authors.initials: FD
authors.lastname: Orata
authors.affiliation: Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Paul C
authors.initials: PC
authors.lastname: Kirchberger
authors.affiliation: Unité Mixte de Recherche 7138, Evolution Paris-Seine, Institut de Biologie Paris-Seine, Université Pierre et Marie Curie, Paris, France.
authors.forename: Raphaël
authors.initials: R
authors.lastname: Méheust
authors.affiliation: Department of Computing Science, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: E Jed
authors.initials: EJ
authors.lastname: Barlow
authors.affiliation: Enteric Diseases Laboratory Branch, Division of Foodborne, Waterborne, and Environmental Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, GA.
authors.forename: Cheryl L
authors.initials: CL
authors.lastname: Tarr
authors.affiliation: Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada yboucher@ualberta.ca.
authors.forename: Yan
authors.initials: Y
authors.lastname: Boucher
mesh_terms: D001483:Base Sequence; D055028:Comparative Genomic Hybridization; D004269:DNA, Bacterial / Q000235:genetics*; D004783:Environmental Microbiology; D019143:Evolution, Molecular; D059647:Gene-Environment Interaction; D005798:Genes, Bacterial; D044404:Genomic Islands; D006801:Humans; D032023:Integrons; D008969:Molecular Sequence Data; D010802:Phylogeny; D014733:Vibrio / Q000235:genetics* / Q000302:isolation & purification; D014734:Vibrio cholerae / Q000235:genetics* / Q000302:isolation & purification; D037521:Virulence Factors / Q000235:genetics
chemical_list: D004269:DNA, Bacterial; D037521:Virulence Factors
keywords: Vibrio cholerae; Vibrio metoecus; comparative genomics; genomic islands; horizontal gene transfer; integron