Presenter: Matthew R. Evans
Advisor(s): Hosni M. Hassan
Author(s): Matthew R. Evans, R. C. Fink, A. Vazquez-Torres, and H. M. Hassan
Graduate Program: Department of Microbiology

Title: The Role of the Global Regulator FNR in the Virulence of Anaerobically Grown Salmonella enterica serovar Typhimurium (ATCC 14028s)

Abstract: As a facultative intracellular pathogen, Salmonella enterica var. Typhimurium (S. Typhimurium) must successfully transition among broad fluctuations in oxygen concentrations encountered during infection of the host milieu. The ability of Salmonella strains to survive and proliferate inside macrophages is crucial for the development of systemic disease. In Escherichia coli, FNR (Fumarate Nitrate Reductase) is a redox-responsive transcriptional regulator that activates or represses the expression of genes involved in anaerobic and aerobic metabolism and in oxidative stress. However, the role of FNR in the virulence of anaerobically grown S. Typhimurium has yet to be determined. Thus, we constructed an isogenic Δfnr strain in the wild-type S. Typhimurium ATCC 14028s and evaluated its ability to survive inside of murine macrophages and after oral infection in the mouse model. Our results showed that the FNR mutant is less virulent in mice and has a diminished capacity to survive inside macrophages. These data clearly demonstrate that, under anoxic conditions, FNR impacts the pathogenicity and virulence of S. Typhimurium.