Bacterial strains designed for immunization frequently have mutations that eliminate lipopolysaccharide O-antigen. These mutants are less immunogenic, however they also have a lowered ability to colonize the intestinal tract and invade intestinal mucosal cells. There is a need then, for a bacterium that has a mutation allowing O-antigen synthesis,...

Streptococcus pneumoniae is the most common cause of community acquired pneumonia. It also results in some two million deaths in children under five and is the major cause of otitis media (ear aches) in the US and Europe. Hence, there is a real need for an effective vaccine against this pathogen. Professor Roy Curtiss and colleagues at Arizona...