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.
Document Type: Research Article
Ume University, Department of Clinical Microbiology, Infectious Diseases and Clinical Bacteriology, and Swedish Defence Research Agency, Division of CBRN Defence and Security, Ume, Sweden. 2:
Centers for Disease Control and Prevention, Division of Vector-Borne Diseases, Fort Collins, CO.
Publication date: November 24, 2010
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