Toward an effective TB vaccine: Analysis of the immune response to a promising candidate

BCG, the only currently approved TB vaccine, has been around for almost a century and is only partially effective. When given to children, BCG is estimated to prevent 20% of infections and to protect half of the infected individuals from developing active TB, and protection fades over time. Given the complicated TB treatment, the rise of adult TB cases in conjunction with the HIV epidemic, and increasing multidrug resistant TB strains, a new and better vaccine is a global health priority. A study published on July 28th inPLOS Pathogens dissects the immune response in mice to an experimental vaccine and shows why it is highly effective. Mycobacteria have a complex cell envelope and use sophisticated transport systems to shuttle proteins across this barrier. Mycobacterium tuberculosis has at least three such systems, called ESX-1, ESX-3, and ESX-5, which are involved in interactions with the human host and contribute to the pathogen’s ability to cause...