Clostridium difficile is a Gram-positive, obligate anaerobe that causes diseases ranging from antibiotic- associated diarrhea to pseudomembranous colitis. In recent years, the incidence and severity of C. difficile infections has increased. Yet there is only limited knowledge of fundamental aspects of pathogenesis, such as the mechanisms used by the bacterium to attach to the intestinal epithelium. Because colonization of the host is a prerequisite for establishing an infection, it is imperative that the mechanisms underlying bacterial attachment to host tissues be defined, as this will drive the much-needed development of additional treatment and prevention options. The long-term goal of this project is to understand how C. difficile attaches to and maintains colonization of the intestinal epithelium. The objective of this proposal is to determine how flagella and Type IV pili as well as the mechanisms controlling their production, impact the ability of C. difficile to colonize host tissues. The central hypothesis of this study is that the bacterial signaling molecule c-di-GMP oppositely regulates the biosynthesis of flagella and Type IV pili, allowing their production at appropriate stages of colonization. This hypothesis will be tested with the following three specific aims.
Specific aim 1 is to determine the effect of the Type IV pilus and is regulation by c-di-GMP on intestinal colonization and virulence.
Specific aim 2 is to determine how flagellar genes are regulated by c-di-GMP and how regulation affects virulence.
Specific aim 3 is to determine the spatial and temporal patterns of Type IV pilus and flagellum production during infection and the importance of coordinating production of these surface organelles on the ability of C. difficile to colonize the host and cause disease. This proposal represents an entirely new area of investigation toward understanding C. difficile disease: the intracellular signaling pathways controlling colonization factors of C. difficile. By defining the regulation and function of flagella and Type IV pili, these studies will significantly expand our knowledge of how C. difficile controls colonization of the host and may reveal targets for inhibition of intestinal colonization to thereby prevent disease.

Public Health Relevance

The proposed research is relevant to the mission of the NIH because it will define mechanisms by which Clostridium difficile, an important human diarrheal pathogen, adheres to the host intestine. The objective of the proposed research is to determine the roles of flagella and Type IV pili, as well as the regulatory pathways controlling their production, in colonizing host tissues. Understanding how C. difficile colonizes the host, a key but poorly understood step in the development of disease, may reveal targets for inhibition of intestinal colonization to thereby prevent disease.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
3R01AI107029-02S1
Application #
9131448
Study Section
Bacterial Pathogenesis Study Section (BACP)
Program Officer
Ranallo, Ryan
Project Start
2013-05-20
Project End
2018-04-30
Budget Start
2014-05-01
Budget End
2015-04-30
Support Year
2
Fiscal Year
2015
Total Cost
$61,774
Indirect Cost
$18,010
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
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McKee, Robert W; Harvest, Carissa K; Tamayo, Rita (2018) Cyclic Diguanylate Regulates Virulence Factor Genes via Multiple Riboswitches in Clostridium difficile. mSphere 3:
Sekulovic, Ognjen; Mathias Garrett, Elizabeth; Bourgeois, Jacob et al. (2018) Genome-wide detection of conservative site-specific recombination in bacteria. PLoS Genet 14:e1007332
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Anjuwon-Foster, Brandon R; Tamayo, Rita (2017) A genetic switch controls the production of flagella and toxins in Clostridium difficile. PLoS Genet 13:e1006701
Purcell, Erin B; McKee, Robert W; Bordeleau, Eric et al. (2016) Regulation of Type IV Pili Contributes to Surface Behaviors of Historical and Epidemic Strains of Clostridium difficile. J Bacteriol 198:565-77
Purcell, Erin B; Tamayo, Rita (2016) Cyclic diguanylate signaling in Gram-positive bacteria. FEMS Microbiol Rev 40:753-73
Edwards, Adrianne N; Tamayo, Rita; McBride, Shonna M (2016) A novel regulator controls Clostridium difficile sporulation, motility and toxin production. Mol Microbiol 100:954-71

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