Studies on the Immunogenic Properties of Bacterium Tularense Variants

Eigelsbach, Henry T.; Braun, Werner; Herring, Ruth

doi:10.1093/infdis/91.1.86

Cited by 36 publications

(41 citation statements)

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“…tularensis subspecies tularensis strain SCHU S4 was derived from an isolate from a case of human tularemia in the US 41 . A clonal seedstock of the bacterium has a median lethal dose in the murine model of disease of less than 1 colony-forming unit 42 .…”

Section: Methodsmentioning

confidence: 99%

The complete genome sequence of Francisella tularensis, the causative agent of tularemia

et al. 2005

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Francisella tularensis is one of the most infectious human pathogens known. In the past, both the former Soviet Union and the US had programs to develop weapons containing the bacterium. We report the complete genome sequence of a highly virulent isolate of F. tularensis (1,892,819 bp). The sequence uncovers previously uncharacterized genes encoding type IV pili, a surface polysaccharide and iron-acquisition systems. Several virulence-associated genes were located in a putative pathogenicity island, which was duplicated in the genome. More than 10% of the putative coding sequences contained insertion-deletion or substitution mutations and seemed to be deteriorating. The genome is rich in IS elements, including IS630 Tc-1 mariner family transposons, which are not expected in a prokaryote. We used a computational method for predicting metabolic pathways and found an unexpectedly high proportion of disrupted pathways, explaining the fastidious nutritional requirements of the bacterium. The loss of biosynthetic pathways indicates that F. tularensis is an obligate host-dependent bacterium in its natural life cycle. Our results have implications for our understanding of how highly virulent human pathogens evolve and will expedite strategies to combat them.

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Section: Methodsmentioning

confidence: 99%

The complete genome sequence of Francisella tularensis, the causative agent of tularemia

et al. 2005

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“…Currently, concerns about biosecurity have rekindled research interest in type A F. tularensis infection and immunity [13]. Most of the original work was performed with a human type A isolate of the pathogen termed, SCHU, and its derivatives particularly SCHU S4 [3][4][5]14]. More recently, SCHU S4 became the sole type A strain to have its genome sequenced [15].…”

Section: Introductionmentioning

confidence: 99%

Virulence comparison in mice of distinct isolates of type A Francisella tularensis

Twine

Shen

Kelly

et al. 2006

Microbial Pathogenesis

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Francisella tularensis subspecies tularensis (type A F. tularensis) is considered to be one of the most virulent of all bacterial pathogens. Mice are extremely susceptible to infection with this subspecies (LD 100 via various inoculation routes is <10 cfu). However, it has not been established whether overt virulence differences exist amongst type A strains of F. tularensis. To this end, the present study compared the virulence of two distinct type A strains, FSC033 and SCHU S4, for naïve mice and mice immunized with the live vaccine strain of the pathogen, F. tularensis LVS. One nominal isolate of SCHU S4 was found to be completely avirulent. Another isolate was highly virulent, but all examined cases appeared somewhat less virulent than FSC033. The implication of these findings for future infection and immunity studies is discussed.

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“…Various strains and variants of this bacterium have been reported to show various degrees of virulence (3,4,14). In many bacterial species, such as Salmonella, two colony types, smooth and rough in their appearance, are easily distinguished and the colony types and the acriflavine agglutination (acf) test are well correlated; the smooth variant is negative in the acf test and the rough variant is positive (10).…”

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confidence: 99%

“…In many bacterial species, such as Salmonella, two colony types, smooth and rough in their appearance, are easily distinguished and the colony types and the acriflavine agglutination (acf) test are well correlated; the smooth variant is negative in the acf test and the rough variant is positive (10). In the case of F. tularensis, however, the colonies are exclusively smooth, and differences in the colony types have been recognized mainly by the acf test (4,11). We have studied the virulence of F. tularensis in mice in terms of the acf test, and demonstrated that the acf test-positive (acf+) variants were exclusively low virulent and the negative (acf-) variants were either high or low virulent (19).…”

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Correlation of the Polysaccharide Antigens of Francisella tularensis with Virulence in Experimental Mice

Fujita

Satô

Watanabe

et al. 1995

Microbiology and Immunology

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Francisella tularensis gives rise to two distinct colony types, acriflavine agglutination test-positive (acf+) and -negative (acf-) colonies. The acf+ variants were exclusively low virulent in mice, while the acfvariants were shown to be either high or low virulent.Three fractions, phosphate-buffered salineextractable without heating, with heating at 60 C, and with heating at 100 C, were obtained from cultures of both the acf+ and acf-variants on agar media, and the polysaccharide antigens in those fractions were quantitated.All of the highly virulent acf-variants possessed a large amount of the polysaccharide antigen in the fraction extractable with heating at 60 C. This antigen was not, however, detected in any of the acf+ variants and one low-virulent acf-variant. It was also detected in a very low amount in some other acf-variants with low virulence. The amount of this polysaccharide antigen was therefore shown to be correlated with bacterial virulence in mice.

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Studies on the Immunogenic Properties of Bacterium Tularense Variants

Cited by 36 publications

References 1 publication

The complete genome sequence of Francisella tularensis, the causative agent of tularemia

The complete genome sequence of Francisella tularensis, the causative agent of tularemia

Virulence comparison in mice of distinct isolates of type A Francisella tularensis

Correlation of the Polysaccharide Antigens of Francisella tularensis with Virulence in Experimental Mice

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