Shigella is the causative agent of bacillary dysentery in humans and primates. Over 200 million cases are reported annually and about 650,000 persons die of shigellosis each year. No effective vaccine exists. Recent bioterrorism concerns increase the importance of understanding Shigella pathogenesis since Shigella has been classified as a category B agent on the NIAID's list of priority pathogens for biodefense research. Shigella is a classic example of an invasive, facultative intracellular pathogen that is exquisitely adapted to living within the cytoplasm of the host cell. Moreover, Shigella has evolved mechanisms to replicate within and exit the host while avoiding the host inflammatory response. Our long term objectives have focused on post-invasion aspects of Shigella pathogenesis including molecular characterization of secreted effector proteins and their role in modulating the host immune response and facilitating intracellular bacterial growth and survival.
The specific aims of this proposal are to: 1) Characterize the bacterial and host factors responsible for the anti-apoptotic effects of Shigella flexneri infection in epithelial cells;and 2) Characterize the role of the Osp proteins with respect to Shigella pathogenesis and the host immune response. Several models and innovative experimental strategies for testing them are proposed. Genetic, biochemical and molecular and cell biology approaches will be utilized in all aims. This research will fill in important gaps in our knowledge of Shigella pathogenesis. Information on how secreted effectors of Shigella modulate host cell survival (anti- apoptosis) and the host inflammatory response can reveal new targets for the design of therapeutic agents. The results of the proposed studies can serve as a paradigm for understanding similar phenotypic traits of other intracellular bacterial pathogens.

Public Health Relevance

Bacillary dysentery (shigellosis) is an acute diarrheal disease caused by bacteria of the Shigella species. Because shigellosis is easily spread from person to person and ingestion of just a few organisms in contaminated food or water is sufficient to cause disease, Shigella are classified as category B biological agents. The aims of this project will help us better understand how this pathogen causes disease, which, in turn, may lead to more effective strategies for prevention and treatment.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI024656-23
Application #
8496661
Study Section
Host Interactions with Bacterial Pathogens Study Section (HIBP)
Program Officer
Mills, Melody
Project Start
1988-12-01
Project End
2014-06-30
Budget Start
2013-07-01
Budget End
2014-06-30
Support Year
23
Fiscal Year
2013
Total Cost
$352,396
Indirect Cost
$122,072
Name
Henry M. Jackson Fdn for the Adv Mil/Med
Department
Type
DUNS #
144676566
City
Bethesda
State
MD
Country
United States
Zip Code
20817
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Zurawski, Daniel V; Mitsuhata, Chieko; Mumy, Karen L et al. (2006) OspF and OspC1 are Shigella flexneri type III secretion system effectors that are required for postinvasion aspects of virulence. Infect Immun 74:5964-76

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