The Francisella tularensis LVS ΔpdpC mutant exhibits a unique phenotype during intracellular infection.
BACKGROUND
A prerequisite for the virulence of the facultative intracellular bacterium Francisella tularensis is effective intramacrophage proliferation, which is preceded by phagosomal escape into the cytosol, and ultimately leads to host cell death. Many components essential for the intracellular life cycle are encoded by a gene cluster, the Francisella pathogenicity island (FPI), constituting a type VI secretion system.


RESULTS
We characterized the FPI mutant ΔpdpC of the live vaccine strain (LVS) of F. tularensis and found that it exhibited lack of intracellular replication, incomplete phagosomal escape, and marked attenuation in the mouse model, however, unlike a phagosomally contained FPI mutant, it triggered secretion of IL-1β, albeit lower than LVS, and markedly induced LDH release.


CONCLUSIONS
The phenotype of the ΔpdpC mutant appears to be unique compared to previously described F. tularensis FPI mutants.
Department of Clinical Microbiology, Clinical Bacteriology and Laboratory for Molecular Infection Medicine Sweden, Umeå University, Umeå SE-901 85, Sweden.
Marie
M
Lindgren
Jeanette E
JE
Bröms
Lena
L
Meyer
Igor
I
Golovliov
Anders
A
Sjöstedt
D000818:Animals; D001428:Bacterial Vaccines / Q000235:genetics; D004195:Disease Models, Animal; D005260:Female; D005604:Francisella tularensis / Q000235:genetics* / Q000254:growth & development / Q000472:pathogenicity*; D008264:Macrophages / Q000382:microbiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D010641:Phenotype; D014406:Tularemia / Q000382:microbiology / Q000473:pathology; D014613:Vaccines, Attenuated / Q000235:genetics; D037521:Virulence Factors / Q000172:deficiency* / Q000235:genetics
D001428:Bacterial Vaccines; D014613:Vaccines, Attenuated; D037521:Virulence Factors