Mycobacterium tuberculosis Early secretory antigenic target 6 kDa (ESAT-6)

The Early secretory antigenic target 6 kDa (ESAT-6) is a critical virulence factor and potent T-cell antigen produced by Mycobacterium tuberculosis [1, 23]. Secreted via the ESX-1 (type VII) secretion system, it plays a primary role in the pathogen's ability to escape from the host phagosome into the cytosol, which is essential for intracellular replication and cell-to-cell spread [6, 25]. ESAT-6 acts as a pore-forming toxin that disrupts host cell membranes and modulates various immune signaling pathways, including the inhibition of Toll-like receptor 2 (TLR2) and the sequestration of beta-2-microglobulin to prevent antigen presentation [9, 26, 28]. Because the gene encoding ESAT-6 is present in virulent M. tuberculosis but absent in the widely used BCG vaccine strain, it serves as a cornerstone for modern diagnostic tools like Interferon-Gamma Release Assays (IGRAs) [18, 24]. It is also a key target for the development of next-generation subunit and live-attenuated tuberculosis vaccines aimed at inducing robust cellular immunity [18, 27]. Beyond diagnostics and vaccines, research into ESAT-6 focuses on small molecule inhibitors that block its secretion or neutralize its membrane-lytic activity to attenuate bacterial pathogenicity [6, 23].

Other names

EsxA6 kDa early secretory antigenic targetRv3875ESAT6

Stimulation of host T-cell mediated immune responses for diagnostic detection or vaccine-induced protection; neutralization of bacterial virulence through inhibition of secretion or membrane-disrupting activity.