Tuberculosis (TB) is the most common cause of death in infectious diseases; it is estimated that approximately 2 million people per year die of TB. The present available TB vaccine is a live attenuated strain, Mycobacterium bovis Bacillus Calmette Guérin (BCG). However, it has been shown that BCG has variable protective efficacy, ranging from 0 to 85% in different clinical experiments.1 Therefore, a new TB vaccine is urgently needed.