Tuberculosisis the second leading cause of death worldwide. The researchers still finding way to eradicate TB. There is an urgent need to discover new drug which is more effective and less toxic to combat drug resistance. This article reports potential of ES-31 antigen as a new drug target. The characterization of ES-31 antigen showed that ES-31 is a 31 kDa protein antigen and has serine protease as well as lipase activities and shown to be a chymotrypsin-like protein which is having catalytic triad responsible for both activities. Addition of serine protease inhibitors (53-76%), metallo protease inhibitor (46-61%), lipase inhibitor (61%) or anti-ES-31 serine protease antibody (89%) strongly inhibited the MTB H37Ra growth in axenic culture.
The importance of excretory secretory ES-31 antigen for the survival of MTB H37Ra and H37Rv bacilli has been shown by 77% and 78% growth inhibition in macrophage culture by protease inhibitor pefabloc. Inhibition of ES-31 leads to growth inhibition of MTB bacilli, suggests that it may be an important drug target for exploring new drugs for tuberculosis.