MR1 and tuberculosis: Despite an increased understanding of mycobacterial MAIT cell-activating ligands, MAIT cell immunoactivation mechanisms, and the clinical associations of MAIT cells in TB disease, it remains unclear (i) whether increased MAIT cell abundance is protective against M. tuberculosis infection, (ii) whether modulation of riboflavin-biosynthetic pathway genes in M. tuberculosis influences MAIT cell activation and bacterial virulence, and (iii) whether adjuvanting BCG with MR1 ligands may enhance its protective efficacy against M. tuberculosis infection.