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Nancy Freitag, Ph.D.

Intracellular pathogens are responsible for devastating amounts of disease worldwide. Unfortunately, our understanding of how these pathogens cause disease is extremely limited, and this lack of knowledge in many instances has severely reduced our ability to develop effective means of combating or preventing infection. My lab studies the intracellular bacterial pathogen Listeria monocytogenes as a model system for understanding how pathogenic intruders survive within infected host cells. L. monocytogenes is associated with food-borne infections, and the bacteria can cause life-threatening diseases in immunocompromised individuals, pregnant women, and neonates. L. monocytogenes is an exceptionally challenging pathogen to control in that it not only has the ability to survive and multiply within mammalian hosts, but it also has a separate and fully functional life in the outside environment where it can be found in diverse locations. We are interested therefore in not only using L. monocytogenes as a model pathogen to understand host-pathogen interactions, but also to understand the processes that enable an environmental organism to become a pathogen capable of causing serious disease in humans.

My lab has focused on the exploration of several aspects of L. monocytogenes pathogenesis. We are interested in determining how the bacterium determines its cellular location within infected hosts and responds with the regulated expression of gene products that promote intracellular survival and replication. We are interested in isolating mutants of L. monocytogenes that behave as though they are growing within the host cell cytosol to define the arsenal of bacterial factors used within infected hosts. We are interested in elucidating host cell defenses that serve to limit bacterial survival and lead to the development of an effective immune response. We are also interested in using L. monocytogenes as an intracellular delivery system to explore the function of gene products produced or delivered into the host cell cytosol by other intracellular parasites in order to identify host cell targets and virulence factor function. My lab uses a variety of biochemical, cellular, and molecular approaches to address key aspects of host-pathogen interplay with the goal of developing a broader understanding of how intracellular microbes cause disease.