Francisella tularensis

What is Francisella?
Francisella tularensis is the causative agent of the disease tularemia. Although rare in the United States, the disease is considered endemic across much of the northern hemisphere.

Our Research Interest:

Ecological conditions contribute to the natural foci of Francisella tularensis. Natural waters, mosquitoes and rodents appear to be important players in the cycle of disease transmission or sources of infection. The disease cycle may also be affected by expression of virulence factors of the bacteria which are induced by environmental stimuli such as temperature, osmolarity and pH. Our lab is interested in what induces expression of these virulence factors and how they then affect the host-bacteria interaction and pathogenesis. Currently we are determining what the relationsip is between Francisella biofilms and aquatic insect larvae. This interaction has the potential to play an important in persistence, dissemination and transmission of the bacterium in the environment.

Once inside the mammalian host, Francisella replicates inside several cell types to include macrophages in a dramatic fashion (see movie at right: mouse macrophages in cell culture are seen infected with GFP expressing F. tularensis LVS, 48 p.i.). Through manipulation of the immune system, the bacteria is capable of replicating to high numbers before the host is capable of controlling the infection. Therefore, rapid identification and treatment of infection is crucial to control of tularemia.

Recently the lab published the first paper investigating the uptake of Francisella from biofilms by aquatic mosquito larvae. This paper was also able to show persistence of the bacteria within the larvae. These findings have potential implications in the ecology and acquisition of the bacteria by potential vector species.