Francisella tularensis is the etiologic agent of tularemia. This gram negative bacterium is a potential agent of bioterrorism because of its high mortality, extremely low infective dose, ability to survive for long periods of time outside of an animal host, and numerous transmission mechanisms including inhalation, ingestion, skin contact, mucous membrane contact, and insect vectors. Little is known about the mechanisms of F. tularensis pathogenesis and host resistance. F. tularensis will survive within macrophages, however macrophage-like cells infected with these organisms become apoptotic within 24 hours following inoculation.
The first aim of this proposal is to examine the mechanism(s) by which F. tularensis provoke host cell death in macrophages. F. tularensis transposon insertion mutants that fail to induce macrophage apoptosis will be isolated and the mutations characterized to define bacterial products responsible for promoting host cell death. These mutant strains will be tested for potential attenuation in a mouse model of tularemia. The mechanism of apoptosis induction by F. tularensis will be determined using mouse gene chips possessing known pro- and anti- apoptotic gene sequences to compare macrophage mRNA levels from control and F. tularensis infected cells.
The second aim i s to isolate Francisella specific CD4 T cell hybrids and determine the differences in the epitopes recognized in C57Bl/6 mice infected with live or heat killed bacteria. E. coli clones expressing the apoptosis inducing genes identified in the first aim will be created and used to isolate specific CD4 T cell hybrids. The ultimate aim will be to create T cell clones of defined cytokine secretion (Th1 or Th2) (by using the defined peptide epitopes) and determine the effect of the clones on pathogenesis and protection.
These aims are directed towards examining the molecular basis for F. tularensis pathogenesis, combined with an approach to elucidate potential immune response targets that could lead to improved prophylaxis against tularemia.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Exploratory/Developmental Grants (R21)
Project #
5R21AI053399-02
Application #
6833459
Study Section
Special Emphasis Panel (ZRG1-BM-1 (02))
Program Officer
Schaefer, Michael R
Project Start
2003-12-15
Project End
2006-11-30
Budget Start
2004-12-01
Budget End
2006-11-30
Support Year
2
Fiscal Year
2005
Total Cost
$255,500
Indirect Cost
Name
University of North Carolina Chapel Hill
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
608195277
City
Chapel Hill
State
NC
Country
United States
Zip Code
27599
Hall, J D; Kurtz, S L; Rigel, N W et al. (2009) The impact of chemokine receptor CX3CR1 deficiency during respiratory infections with Mycobacterium tuberculosis or Francisella tularensis. Clin Exp Immunol 156:278-84
Craven, Robin R; Hall, Joshua D; Fuller, James R et al. (2008) Francisella tularensis invasion of lung epithelial cells. Infect Immun 76:2833-42
Fuller, James R; Craven, Robin R; Hall, Joshua D et al. (2008) RipA, a cytoplasmic membrane protein conserved among Francisella species, is required for intracellular survival. Infect Immun 76:4934-43
Hall, Joshua D; Craven, Robin R; Fuller, James R et al. (2007) Francisella tularensis replicates within alveolar type II epithelial cells in vitro and in vivo following inhalation. Infect Immun 75:1034-9
Kawula, Thomas H; Hall, Joshua D; Fuller, James R et al. (2004) Use of transposon-transposase complexes to create stable insertion mutant strains of Francisella tularensis LVS. Appl Environ Microbiol 70:6901-4