Salmonella, Mycobacterium and Histoplasma are facultative intracellular pathogens that live inside phagosomes of host macrophages. They all cause AIDS-defining illnesses, and the investigator's long-term goal is to understand the development of immunity against such pathogens. CD4+ T cells are also required for immune mice to resist virulent Salmonella, providing a model of protective host functions which can successfully combat a macrophage-tropic infection. However, the specific bacterial antigens (Ags) recognized by Salmonella-immune hosts are largely unknown. Two proteins expressed in the surface-exposed """"""""compartment"""""""" of Salmonella are recognized by CD4+ T cells from immune mice. One is a flagellar protein also recognized by T cells from humans immunized with Salmonella. The other is an unidentified protein expressed by most Enterobacteriaceae, including E. coli, Yersinia, Shigella, and Enterobacter. Both proteins are regulated in a fashion suggesting part of the Salmonella intracellular survival strategy is to down-regulate expression of bacterial surface Ags recognized by CD4+ T cells.
In AIM I, the diversity of Salmonella Ags recognized by CD4+ T cells from immune mice will be determined using SDS-PAGE fractionated bacteria as Ag, and bacterial expression of these Ags will be characterized with respect to compartmentalization and regulation using T cell clones. The studies will provide insight into the nature of Ags recognized by CD4+ T cells, the environmental signals affecting bacterial processing Salmonella for T cell responses.
In AIM 2, genes encoding Ags recognized by T cell clones will be identified by expression cloning or sequencing analysis of biochemically purified Ags. This work may reveal gene products useful as markers of cellular immunity to Salmonella in humans.
In AIM 3, murine infection with Salmonella strains expressing a model Ag in various compartments of the bacterial cell will be used to directly test if compartmentalization of bacterial Ag alters its significance for surveillance by T cells. Primary and secondary CD4+ T cell responses generated by these stains will be quantified using ELISPOT and flow cytometry, and the effectiveness of an Ag-specific immune response against these strains will be tested in vivo. These studies will provide insight into the nature of Ags recognized by CD4+ T cells responding to pathogens similarly adapted for life in phagosomes.
In AIM 4, the functional importance of Ags identified in AIMS 1 & 2 will be determined by testing purified Ags for their ability to stimulate protective immunity against challenge by virulent Salmonella. The protective Ags identified will be excellent candidates for components of subunit vaccines and markers of cellular immunity in humans.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI047242-05
Application #
6836493
Study Section
Bacteriology and Mycology Subcommittee 2 (BM)
Program Officer
Alexander, William A
Project Start
2001-01-01
Project End
2007-12-31
Budget Start
2005-01-01
Budget End
2007-12-31
Support Year
5
Fiscal Year
2005
Total Cost
$338,082
Indirect Cost
Name
University of Washington
Department
Pathology
Type
Schools of Medicine
DUNS #
605799469
City
Seattle
State
WA
Country
United States
Zip Code
98195
Bergsbaken, Tessa; Fink, Susan L; Cookson, Brad T (2009) Pyroptosis: host cell death and inflammation. Nat Rev Microbiol 7:99-109
Deatherage, Brooke L; Lara, J Cano; Bergsbaken, Tessa et al. (2009) Biogenesis of bacterial membrane vesicles. Mol Microbiol 72:1395-407
Fink, Susan L; Bergsbaken, Tessa; Cookson, Brad T (2008) Anthrax lethal toxin and Salmonella elicit the common cell death pathway of caspase-1-dependent pyroptosis via distinct mechanisms. Proc Natl Acad Sci U S A 105:4312-7
Alaniz, Robert C; Deatherage, Brooke L; Lara, Jimmie C et al. (2007) Membrane vesicles are immunogenic facsimiles of Salmonella typhimurium that potently activate dendritic cells, prime B and T cell responses, and stimulate protective immunity in vivo. J Immunol 179:7692-701
Fink, Susan L; Cookson, Brad T (2007) Pyroptosis and host cell death responses during Salmonella infection. Cell Microbiol 9:2562-70
Bergsbaken, Tessa; Cookson, Brad T (2007) Macrophage activation redirects yersinia-infected host cell death from apoptosis to caspase-1-dependent pyroptosis. PLoS Pathog 3:e161
Cummings, Lisa A; Wilkerson, W David; Bergsbaken, Tessa et al. (2006) In vivo, fliC expression by Salmonella enterica serovar Typhimurium is heterogeneous, regulated by ClpX, and anatomically restricted. Mol Microbiol 61:795-809
Alaniz, Robert C; Cummings, Lisa A; Bergman, Molly A et al. (2006) Salmonella typhimurium coordinately regulates FliC location and reduces dendritic cell activation and antigen presentation to CD4+ T cells. J Immunol 177:3983-93
Fink, Susan L; Cookson, Brad T (2006) Caspase-1-dependent pore formation during pyroptosis leads to osmotic lysis of infected host macrophages. Cell Microbiol 8:1812-25
Cummings, Lisa A; Barrett, Sara L Rassoulian; Wilkerson, W David et al. (2005) FliC-specific CD4+ T cell responses are restricted by bacterial regulation of antigen expression. J Immunol 174:7929-38

Showing the most recent 10 out of 17 publications