Francisella tularensis vaccines.

Francisella tularensis is the causative agent of tularaemia, a disease which occurs naturally in some countries in the northern hemisphere. Recently, there has been a high level of interest in devising vaccines against the bacterium because of the potential for it to be used as a bioterrorism agent. Previous human volunteer studies have shown that a strain of F. tularensis [the live vaccine strain (LVS)] that has been attenuated by laboratory passage is effective in humans as a vaccine against airborne disease. However, for a variety of reasons it seems unlikely that the LVS strain will be licensed for use in humans. Against this background there is an effort to devise a licensable vaccine against tularaemia. The prospects for a killed whole-cell subunit of live attenuated vaccine are reviewed. A rationally attenuated mutant seems the most likely route to a new tularaemia vaccine.