Mycobacterium 'habana' TMC 5135 as a vaccine candidate against tuberculosis: In vitro studies

Abstract

Background: Tuberculosis (TB) is one of the biggest problems of global health, at present. Bacillus-Calmette-Guérin is the only vaccine available against this disease. It protects only against the severe forms of TB in the childhood, which is a challenge in the search of new vaccine candidates. Taking into account the protective history of Mycobacterium 'habana' against experimental TB, we proposed to provide the elements that support the use of M. 'habana' TMC 5135 as a vaccine candidate against TB by infection studies in murine macrophages cell cultures. Methods: The production of microbicidal compounds dependent on oxygen metabolism as nitric oxide and hydrogen peroxide by murine peritoneal macrophages was detected. The invasive and toxigenic capacity of M. 'habana' to infect this cell type was also evaluated through the quantification of intracellular alive bacillus and 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide assay, respectively. Results: The results suggest that M. 'habana' TMC 5135 is able to persist into peritoneal macrophages, to resist the effectors mechanisms of respiratory burst, and to keep the viability of the target cell. The demonstration of these effector mechanisms and the survival capacity of M. 'habana' in this niche are relevant aspects of this research assuring the continuity of this candidate to next phases of preclinical development. Conclusion: The present investigation contributes to the characterization of the infection by this mycobacteria in its main target cells of innate immunity and it suggest future investigations to evaluate the activation of effector mechanisms of the innate immunity against this candidate.