TB vaccine boost

A retooled version of the vaccine currently used against tuberculosis shows superior protection against the pathogen in animal studies, according to a report by researchers from Germany, England, France and the Netherlands. The researchers engineered a vaccine strain of Mycobacterium bovis that secretes listeriolysin, a protein that pierces the membranes of phagosomes that harbor tuberculosis bacteria. This allows better T cell-mediated immunity than is stimulatedby the currently available vaccine, BCG, which offers only little protection to adults and has limited efficacy against newly emerging isolates of the tuberculosis bacterium. The researchers also deleted the urease C gene of the bacille Calmette-Guerin strain to create the ideal pH environment for listeriolysin.