Bacillus Calmette-Guerin

Approximately one third of the world population is infected by Mycobacterium tuberculosis, and a greater and continuing factor that is bolstering the ongoing tuberculosis (TB) epidemic is the human immune deficiency virus (HIV). Further complicating the issue, multidrug resistance (MDR) has arisen worldwide, and by early 2010, 58 countries had reported at least one case of extensively drug resistant TB . For all these reasons, TB prevention through vaccination is a key global health priority. Various vaccines have been shown to reduce the risk of disease and mortality due to TB in man, but only one has been used in global immunization programs: the M. bovis bacillus Calmette-Guérin (BCG). BCG is an attenuated live vaccine administered at birth to children in most countries where TB is endemic. It is the vaccine most widely used all over the world, and an estimated three billion doses have been administered to date. Despite having reduced the burden of TB in many zones, the BCG has various limitations and so the development of more efficacious vaccines against TB is an extremely urgent issue. The ideal vaccine should prevent both the initial tubercle infection and the development of active disease, or reactivation in previously infected healthy hosts as well as in particularly vulnerable populations (HIV-infected and other immunocompromised individuals).