The present invention includes the discovery of a strain of Mycobacterium comprising an expression vector encoding a di-adenylate cyclase enzyme. The Mycobacterium is selected from the group consisting of Mycobacterium tuberculosis, Mycobacterium bovis, or a combination thereof and the preferred strain of Mycobacterium is BCG. The preferred expression vector is a mycobacterial expression vector including an hsp60 promoter and a DNA sequence of diadenylate cyclase (disA), or a functional part thereof. The strains of Mycobacterium are used in therapeutic applications including tuberculosis and cancer.