The Family Francisellaceae

Colquhoun, Duncan J.; Larsson, Pär; Duodu, Samuel; Forsman, Mats

doi:10.1007/978-3-642-38922-1_236

Cited by 10 publications

(14 citation statements)

References 285 publications

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“…The genus Allofrancisella contains three validly published species, of which all have been isolated from water samples collected from cooling towers of air conditioning systems [ 1 ]. Despite this diversity within the Francisellaceae, and nine different Francisella species ( Table A1 ), only the three F. tularensis subspecies, i.e., subspecies tularensis (type A), subspecies holarctica (type B), and subspecies mediasiatica [ 3 ], are of significant clinical relevance to humans. The subspecies holarctica and tularensis cause tularemia in humans [ 4 ].…”

Section: Introductionmentioning

confidence: 99%

Reorganized Genomic Taxonomy of Francisellaceae Enables Design of Robust Environmental PCR Assays for Detection of Francisella tularensis

et al. 2021

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In recent years, an increasing diversity of species has been recognized within the family Francisellaceae. Unfortunately, novel isolates are sometimes misnamed in initial publications or multiple sources propose different nomenclature for genetically highly similar isolates. Thus, unstructured and occasionally incorrect information can lead to confusion in the scientific community. Historically, detection of Francisella tularensis in environmental samples has been challenging due to the considerable and unknown genetic diversity within the family, which can result in false positive results. We have assembled a comprehensive collection of genome sequences representing most known Francisellaceae species/strains and restructured them according to a taxonomy that is based on phylogenetic structure. From this structured dataset, we identified a small number of genomic regions unique to F. tularensis that are putatively suitable for specific detection of this pathogen in environmental samples. We designed and validated specific PCR assays based on these genetic regions that can be used for the detection of F. tularensis in environmental samples, such as water and air filters.

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Section: Introductionmentioning

confidence: 99%

Reorganized Genomic Taxonomy of Francisellaceae Enables Design of Robust Environmental PCR Assays for Detection of Francisella tularensis

et al. 2021

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“…However, as expected, there are similarities but important differences between these species when their capsules and polysaccharides are compared. F. novicida has been reported to be unencapsulated (75). Recently, we showed that F. novicida produces a CLC similar to that of the more virulent F. tularensis when grown in a similar manner on chemically defined medium (24, 67) (Fig.…”

Section: The Similar But Distinct Polysaccharides Of F Novicidamentioning

confidence: 80%

The Francisella tularensis Polysaccharides: What Is the Real Capsule?

Catanzaro

Inzana

2020

Microbiol Mol Biol Rev

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SUMMARY Francisella tularensis is a tier 1 select agent responsible for tularemia in humans and a wide variety of animal species. Extensive research into understanding the virulence factors of the bacterium has been ongoing to develop an efficacious vaccine. At least two such virulence factors are described as capsules of F. tularensis: the O-antigen capsule and the capsule-like complex (CLC). These two separate entities aid in avoiding host immune defenses but have not been clearly differentiated. These components are distinct and differ in composition and genetic basis. The O-antigen capsule consists of a polysaccharide nearly identical to the lipopolysaccharide (LPS) O antigen, whereas the CLC is a heterogeneous complex of glycoproteins, proteins, and possibly outer membrane vesicles and tubes (OMV/Ts). In this review, the current understanding of these two capsules is summarized, and the historical references to “capsules” of F. tularensis are clarified. A significant amount of research has been invested into the composition of each capsule and the genes involved in synthesis of the polysaccharide portion of each capsule. Areas of future research include further exploration into the molecular regulation and pathways responsible for expression of each capsule and further elucidating the role that each capsule plays in virulence.

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“…Together with the clade formed by F. frigiditurris, a species recently isolated from the water of a cooling tower [46], it precedes the split of four other major clades in which all the other Francisella species are subdivided in full accord with the recently proposed genome-based Francisella phylogeny [46,47]. One of the four clades is specific to species, such as F. tulariensis and F. novicida, that are pathogenic to terrestrial hosts, and F. persica (formerly Wolbachia persica) isolated from ticks [12,17]. The second one includes species such as F. noatuniensis that are pathogenic to fish, as well as F. salina isolated from a seawater sample [46].…”

Section: Phylogenetic Relationshipsmentioning

confidence: 93%

“…The second one includes species such as F. noatuniensis that are pathogenic to fish, as well as F. salina isolated from a seawater sample [46]. The third one includes species such as F. endociliophora and F. halioticida isolated from marine hosts, together with F. uliginis isolated from a seawater sample [9,12,46]. And the fourth one is specific to Francisella species that have been isolated from waters of cooling systems, and are usually described as 'environmental'…”

Section: Phylogenetic Relationshipsmentioning

confidence: 99%

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A New Species of the γ-Proteobacterium Francisella, F. adeliensis Sp. Nov., Endocytobiont in an Antarctic Marine Ciliate and Potential Evolutionary Forerunner of Pathogenic Species

et al. 2018

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The study of the draft genome of an Antarctic marine ciliate, Euplotes petzi, revealed foreign sequences of bacterial origin belonging to the γ-proteobacterium Francisella that includes pathogenic and environmental species. TEM and FISH analyses confirmed the presence of a Francisella endocytobiont in E. petzi. This endocytobiont was isolated and found to be a new species, named F. adeliensis sp. nov.. F. adeliensis grows well at wide ranges of temperature, salinity, and carbon dioxide concentrations implying that it may colonize new organisms living in deeply diversified habitats. The F. adeliensis genome includes the igl and pdp gene sets (pdpC and pdpE excepted) of the Francisella pathogenicity island needed for intracellular growth. Consistently with an F. adeliensis ancient symbiotic lifestyle, it also contains a single insertion-sequence element. Instead, it lacks genes for the biosynthesis of essential amino acids such as cysteine, lysine, methionine, and tyrosine. In a genome-based phylogenetic tree, F. adeliensis forms a new early branching clade, basal to the evolution of pathogenic species. The correlations of this clade with the other clades raise doubts about a genuine free-living nature of the environmental Francisella species isolated from natural and man-made environments, and suggest to look at F. adeliensis as a pioneer in the Francisella colonization of eukaryotic organisms.

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The Family Francisellaceae

Cited by 10 publications

References 285 publications

Reorganized Genomic Taxonomy of Francisellaceae Enables Design of Robust Environmental PCR Assays for Detection of Francisella tularensis

Reorganized Genomic Taxonomy of Francisellaceae Enables Design of Robust Environmental PCR Assays for Detection of Francisella tularensis

The Francisella tularensis Polysaccharides: What Is the Real Capsule?

A New Species of the γ-Proteobacterium Francisella, F. adeliensis Sp. Nov., Endocytobiont in an Antarctic Marine Ciliate and Potential Evolutionary Forerunner of Pathogenic Species

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