Mini Review Volume 1 Issue 3 -April 2017 DOI: 10.19080/IJOPRS.2017.01.555564 Int J Pul & Res Sci Copyright © All rights are reserved by Antonia Isabel Castillo Rodal Mycobacterium bovis BCG: Close to Reach an End to the Puzzle Castillo-Rodal AI* and López-Vidal Y Programa de Inmunología Molecular Microbiana, Departamento de Microbiología y Parasitología, Facultad de Medicina. Universidad Nacional Autónoma de México, México Submission:February 22, 2017; Published: April 25, 2017 *Corresponding author: Antonia Isabel Castillo Rodal, PhD. Programa de Inmunología Molecular Microbiana, Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, Avenida Universidad 3000, Facultad de Medicina, Edificio de Investigación, 4to piso, Col. Universidad Nacional Autónoma de México-CU, Deleg. Coyoacán, CP 04510, Mexico, Tel: ; Email Abstract The vaccine M. bovis BCG is the most applied worldwide nevertheless, it is protective efficacy especially against pulmonary tuberculosis is very variable. Diverse investigations are carried out to improve by recombinant BCG or to a new prototype vaccine. Neither, candidates for vaccines have increased the protection that confers the current BCG vaccine. While preclinical essays are realized with the most recent BCG vaccines. Although there is not sufficient knowledge based on recent discovery processes of biological such as, RNA that plays a very important role in the interaction cell host-M. bovis BCG over some, provide many answers that we are no aware, regarding to the protection against tuberculosis due to BCG vaccination. Keywords: BCG vaccine; Immune response; Protection Abbreviations: M. bovis: Mycobacterium bovis; Mtb: Mycobacterium tuberculosis RD: Differentiation regions; DU: Duplication Units; M Avium: Mycobacterium Avium; NTM: Nontuberculous Mycobacteria; M Vaccae: Mycobacterium Vaccae; DC: Dendritic Cells Introduction At present times. The Calmette and Güerin vaccine generated from Mycobacterium bovis (M. bovis), is the only one available all over the world to fight against tuberculosis. Even although it is the most employed vaccine in the world and it has almost one hundred years of use, tuberculosis has not been eradicated and each year this disease causes 1.3 million deaths and almost 9 million of new cases each year [1]. Different human research has sown this BCG vaccine has an enormous variability in its protective efficacy (0%-80%). These reports have been explained based on the presence of different factors, as it is the case of parasitic infestations, or the presence of viral, fungal or bacterial infections, known stimulants of the unspecific immune response. Also, it could be related to several different characteristics of the population studied as it is the case of age, ethnicity, socioeconomic level or the genotypic differences in the several BCG strains used for the vaccine. The inconsistent protection of the vaccine against pulmonary tuberculosis has been followed by several meta-analysis where a different degree of efficacy among several strains was documented. Data from this analysis has shown that BCG vaccine could prevent from the severe forms of the disease (miliary and meningitis tuberculosis) in 60%-70% of the cases. Additionally, a protector effect against pulmonary tuberculosis was found in 50% of these studies [2]. From these findings, a comparative genetic analysis was made between two pathogen strains: Mycobacterium tuberculosis (Mtb) and M. bovis and BCG strains. Differentiation regions (RD) and duplication units (DU) were studied. RD1 and RD3 were lacking in the complete set of BCG strains and this happened during the thirteen years (1863-1933) that the bacillus M. bovis was cultivated by hundreds of passes. These findings confirmed that RD1 codifies the ESX-1 secretion system and it is conformed for two antigens with a high degree of immunogenicity (ESAT6 and CFP-10) besides being needed for the virulence of the strains. The same research team identified the irregular presence of RD2 region absent in some strain and present in others. Sometimes mpt64 antigen was not functional despite its presence. These findings cannot ascertain their efficacy and neither suggest that virulence is reduced in case of its deletion [3]. Int J Pul & Res Sci 1(3): IJOPRS.MS.ID.555564 (2017) 001