Mycobacterium tuberculosis (M.tb) is a pathogen found worldwide that infects humans causing tuberculosis (TB), a transmissible disease resulting in very high mortality and morbidity. It is estimated that a third of the world's population is latently infected with M.tb, and these people carry a 10% lifetime risk of developing active life-threatening disease. In 2013, there were 9 million new cases worldwide and 1.5 million people died of TB. Co-infection with human immunodeficiency virus (HIV) greatly increases risk of TB reactivation and death. TB diagnosis is challenging and drug treatment can be prolonged, harmful, costly and complex. For these reasons an effective vaccine is a global public health priority.