title: Virulence comparison in mice of distinct isolates of type A Francisella tularensis.
abstract: 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 (LD100 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.
authors.affiliation: National Research Council Canada, Institute for Biological Sciences, Ottawa, Ont. K1A 0R6, Canada.
authors.forename: Susan M
authors.initials: SM
authors.lastname: Twine
authors.forename: Hua
authors.initials: H
authors.lastname: Shen
authors.forename: John F
authors.initials: JF
authors.lastname: Kelly
authors.forename: Wangxue
authors.initials: W
authors.lastname: Chen
authors.forename: Anders
authors.initials: A
authors.lastname: Sjöstedt
authors.forename: J Wayne
authors.initials: JW
authors.lastname: Conlan
mesh_terms: D000818:Animals; D015169:Colony Count, Microbial; D004195:Disease Models, Animal; D005260:Female; D005604:Francisella tularensis / Q000145:classification / Q000472:pathogenicity*; D008099:Liver / Q000382:microbiology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D013154:Spleen / Q000382:microbiology; D016019:Survival Analysis; D014406:Tularemia / Q000276:immunology / Q000382:microbiology*; D014774:Virulence