Mycobacterium tuberculosis has been called “the perfect pathogen.” These bacteria hijack human macrophages, persist inside the cells to evade immune destruction, and then prevent the macrophage from undergoing programmed cell death. This provides a niche where they grow in a protected environment that is hard to reach with antibiotics.

Despite 132 years of study, no toxin had ever been found for the deadly pathogen Mycobacterium tuberculosis, which infects 9 million people a year and kills more than 1 million.