| 1. |
- Vogler, Amy J, et al.
(author)
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Phylogeography of Francisella tularensis : global expansion of a highly fit clone
- 2009
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In: Journal of Bacteriology. - : American Society for Microbiology. - 0021-9193 .- 1098-5530. ; 191:8, s. 2474-2484
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Journal article (peer-reviewed)abstract
- 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. Phylogenetic 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.
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| 2. |
- Birdsell, Dawn N, et al.
(author)
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Francisella tularensis subsp. tularensis group A.I, United States
- 2014
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In: Emerging Infectious Diseases. - : Centers for Disease Control and Prevention (CDC). - 1080-6040 .- 1080-6059. ; 20:5, s. 861-865
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Journal article (peer-reviewed)abstract
- We used whole-genome analysis and subsequent characterization of geographically diverse strains using new genetic signatures to identify distinct subgroups within Francisella tularensis subsp. tularensis group A.I: A.I.3, A.I.8, and A.I.12. These subgroups exhibit complex phylogeographic patterns within North America. The widest distribution was observed for A.I.12, which suggests an adaptive advantage.
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| 3. |
- Johansson, Anders, 1966-, et al.
(author)
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Genotyping of Francisella tularensis, the causative agent of tularemia
- 2010
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In: Journal of AOAC International. - 1060-3271 .- 1944-7922. ; 93:6, s. 1930-1943
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Journal article (peer-reviewed)abstract
- Francisella tularensis is a facultative, intracellular, zoonotic pathogen and the causative agent of tularemia. Historically, F. tularensis has been subdivided into subspecies on the basis of phenotypic traits, including biochemical reactivity and virulence. More recently, a number of genotypic methods, ranging from relatively insensitive methods to full genome sequencing, have been used to investigate genetic diversity within F. tularensis. These analyses indicate that F. tularensis is a pathogen of low sequence diversity with pair-wise average nucleotide identities > 99.2% across subspecies. Nonetheless, genomic rearrangements and sequence deletions exist between and within F. tularensis subspecies, creating polymorphisms detectable by genotyping methods. Genetic subpopulations intermediate to the subspecies and strain level have been identified within F. tularensis subsp. tularensis and F. tularensis subsp. holarctica by several different typing methods. These genetic subpopulations have been associated with differences in disease severity, geographic distribution, and transmission patterns. For example, one F. tularensis subsp. tularensis subpopulation has been found to be significantly associated with mortality in humans. Additionally, genotypic analyses of Francisella spp. have provided information for use in the rational design of strain panels for validation of F. tularensis diagnostic tests. This review provides a guide to the various F. tularensis genotyping methods.
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| 4. |
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