Mycobacterium bovis Bacillus Calmette-Guerin (BCG) and BCG-based vaccines against tuberculosis

Tuberculosis (TB) is the second leading infectious cause of mortality worldwide with about two million deaths per year. The only licensed TB vaccine, Mycobacterium bovis bacillus Calmette-Guerin (BCG) shows limited protection efficacy suggesting an improved vaccination strategy is required. Recently, several TB vaccine candidates have entered clinical trials. These vaccine candidates are live mycobacterial vaccines designed to replace BCG or subunit vaccines designed to boost immunity induced by BCG. Vaccines with different strategy such as therapeutic vaccines, which can also be used in combination with drug therapy, are in the early stages of development to resolve latent TB or reactivation from the latent state. In this review, we discuss about development of BCG and BCG-based vaccines and further studies necessary for novel TB vaccine development to sterilize tuberculosis.