A genomic analysis of Mycobacterium immunogenum strain CD11_6 and its potential role in the activation of T cells against Mycobacterium tuberculosis.

Background: Mycobacterium tuberculosis (Mtb) is an etiological agent of tuberculosis (TB). Tuberculosis is a mounting problem worldwide. The only available vaccine BCG protects the childhood but not adulthood form of TB. Therefore, efforts are made continuously to improve the efficacy of BCG by supplementing it with other therapies. Consequently, we explored the possibility of employing Mycobacterium immunogenum (Mi) to improve BCG potential to protect against Mtb.

Results: We report here the genome mining, comparative genomics, immunological and protection studies employing strain CD11_6 of Mi. Mycobacterium immunogenum was isolated from duodenal mucosa of a celiac disease patient. The strain was whole genome sequenced and annotated for identification of virulent genes and other traits that may make it suitable as a potential vaccine candidate. Virulence profile of Mi was mapped and compared with two other reference genomes i.e. virulent Mtb strain H37Rv and vaccine strain Mycobacterium bovis (Mb) AFF2122/97. This comparative analysis revealed that Mi is less virulent, as compared to Mb and Mtb, and contains comparable number of genes encoding for the antigenic proteins that predict it as a probable vaccine candidate. Interestingly, the animals vaccinated with Mi showed significant augmentation in the generation of memory T cells and reduction in the Mtb burden.

Conclusion: The study signifies that Mi has a potential to protect against Mtb and therefore can be a future vaccine candidate against TB.