Disarming One of the Deadliest Pathogens
Francisella tularensis, the cause of tularemia and one of the deadliest respiratory pathogens in existence, is considered a potential biological weapon because it is readily aerosolized and exhibits a high degree of infectivity and lethality in humans. While a live attenuated vaccine strain has been developed, it remains unlicensed because scientists have been unable to understand the basis for its attenuated virulence. In an attempt to find an acceptable live attenuated vaccine strain, researchers from Harvard Medical School examined the mechanism behind one reason the pathogen is so lethal. The first line of defense against a bacterial pathogen is innate immunity, which slows the progress of infection to allow time for adaptive immunity to develop. F. tularensis suppresses the early innate immune response, allowing the pathogen to kill its host before adaptive immunity develops, using a specific lipopolysaccharide (LPS.) In this study the researchers show that a strain of the pathogen lacking this specific LPS is attenuated in mice and specifically elicits an innate immune response. When immunized with the strain, mice were protected against challenge by a highly virulent strain of the bacteria. This study has identified not only a novel LPS modification important for microbial virulence, but also offers a new vaccine candidate.
Lessons from a Decade of Plague in a Port City
A cluster of human plague cases over a 10-year period in the seaport city of Mahajanga Madagascar after a 62-year plague-free period provided researchers from Arizona and Madagascar with an opportunity to study plague dynamics in an urban environment, especially since historically plague entered new geographic areas through port cities such as this. Most of the isolates found during t
|Contact: Jim Sliwa|
American Society for Microbiology