Objective:To examine the host-pathogen interaction between mycobacteria and defensive cells of striped bass (Morone saxatilis).
One of the first lines of defense against disease-causing bacteria in fish and mammals is a type of cell called a macrophage. Macrophages take in bacteria and foreign material in a process called phagocytosis, and digest this material by producing reactive chemicals and degradative enzymes. In mammals, disease-causing mycobacteria have the capability to avoid the killing mechanisms of macrophages and can survive as intracellular parasites rather than being digested.
The interaction between aquatic mycobacteria and fish macrophages is poorly understood. Using a combination of electron microscopy and functional in vitro assays, we are exploring the ability of striped bass macrophages to kill mycobacteria, as well as the mechanisms by which mycobacteria resist killing.
In addition to cellular assays, we are examining the defensive response of striped bass to mycobacteria on a whole-fish level. In a collaborative effort with the National Fish Health Research Laboratory (U.S. Geologic Survey), we are conducting controlled studies in which striped bass are exposed to various species of mycobacteria, including Mycobacterium marinum, M. shottsii, and the soil saprophyte M. gordonae. Using histological and bacteriological methods, these studies address the relative ability of different mycobacterial species to cause disease, as well as the ability of striped bass to contain and control infection.
Graduate Student Investigator:
- David Gauthier