Novel insights into Mycobacterium antigen Ag85 biology and implications in countermeasures for M. tuberculosis.

Tuberculosis remains one of the most prevalent and deadly infectious diseases, largely due to the emergence of multidrug-resistant and extensive drug-resistant Mycobacterium tuberculosis, especially the coinfection with HIV. Mycobacterium Ag85 complex (Ag85A, B, and C), with a carboxylesterase consensus sequence and conserved surface catalysis residues, involves in cell wall biosynthesis and the trigger of the host immune response. The physiological function, structures, distributions, and molecular mechanisms of regulations as well as their implications in novel vaccines and diagnostics against tuberculosis are summarized. Special focus is the regulation underlying the Ag85 expression. This will facilitate in-depth understanding of the role of Ag85 and developing better novel measures against M. tuberculosis infection.