Phylogeography of francisella tularensis: Global expansion of a highly fit clone

Amy J. Vogler, Dawn Birdsell, Lance B. Price, Jolene R. Bowers, Stephen M. Beckstrom-Sternberg, Raymond K. Auerbach, James S. Beckstrom-Sternberg, Anders Johansson, Ashley Clare, Jordan L. Buchhagen, Jeannine M. Petersen, Talima Pearson, Josée Vaissaire, Michael P. Dempsey, Paul Foxall, David M. Engelthaler, David M. Wagner, Paul Keim

Research output: Contribution to journalArticlepeer-review

160 Scopus citations


Francisella tularensis contains several highly pathogenic subspecies, including Francisella tularensis subsp. holarctica, whose distribution is circumpolar in the northern hemisphere. The phylogeography of these subspecies and their subclades was examined using whole-genome single nucleotide polymorphism (SNP) analysis, high-density microarray SNP genotyping, and real-time-PCR-based canonical SNP (canSNP) assays. Almost 30,000 SNPs were identified among 13 whole genomes for phylogenetic analysis. We selected 1,655 SNPs to genotype 95 isolates on a high-density microarray platform. Finally, 23 clade- and subclade-specific canSNPs were identified and used to genotype 496 isolates to establish global geographic genetic patterns. We confirm previous findings concerning the four subspecies and two Francisella tularensis subsp. tularensis subpopulations and identify additional structure within these groups. We identify 11 subclades within F. tularensis subsp. holarctica, including a new, genetically distinct subclade that appears intermediate between Japanese F. tularensis subsp. holarctica isolates and the common F. tularensis subsp. holarctica isolates associated with the radiation event (the B radiation) wherein this subspecies spread throughout the northern hemisphere. Phy- logenetic analyses suggest a North American origin for this B-radiation clade and multiple dispersal events between North America and Eurasia. These findings indicate a complex transmission history for F. tularensis subsp. holarctica.

Original languageEnglish (US)
Pages (from-to)2474-2484
Number of pages11
JournalJournal of Bacteriology
Issue number8
StatePublished - Apr 2009

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology


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