ESAT-6 or Early Secreted Antigenic Target 6 kDa, is produced by ''

Mycobacterium tuberculosis ''Mycobacterium tuberculosis'' (M. tb) is a species of pathogenic bacteria in the family Mycobacteriaceae and the causative agent of tuberculosis. First discovered in 1882 by Robert Koch, ''M. tuberculosis'' has an unusual, waxy coating on its c ...

'', it is a

secretory protein A secretory protein is any protein, whether it be endocrine or exocrine, which is secreted by a cell. Secretory proteins include many hormones, enzymes, toxins, and antimicrobial peptides. Secretory proteins are synthesized in the endoplasmic ret ...

and potent

T cell A T cell is a type of lymphocyte. T cells are one of the important white blood cells of the immune system and play a central role in the adaptive immune response. T cells can be distinguished from other lymphocytes by the presence of a T-cell r ...

antigen In immunology, an antigen (Ag) is a molecule or molecular structure or any foreign particulate matter or a pollen grain that can bind to a specific antibody or T-cell receptor. The presence of antigens in the body may trigger an immune response. ...

. It is used in

tuberculosis diagnosis Tuberculosis is diagnosed by finding ''Mycobacterium tuberculosis'' bacteria in a clinical specimen taken from the patient. While other investigations may strongly suggest tuberculosis as the diagnosis, they cannot confirm it. A complete medical ...

by the whole blood interferon γ test

QuantiFERON Interferon-gamma release assays (IGRAs) are diagnostic tools for latent tuberculosis infection (LTBI). They are surrogate markers of ''Mycobacterium tuberculosis'' infection and indicate a cellular immune response to ''M. tuberculosis'' if the lat ...

-TB Gold, in conjunction with

CFP-10 CFP-10 within bacterial proteins (also known as ESAT-6-like protein esxB or secreted antigenic protein MTSA-10 or 10 kDa culture filtrate antigen CFP-10) is a protein that is encoded by the ''esxB'' gene. CFP-10 is a 10 kDa secreted antigen from ...

and TB7.7. ESAT-6 has been shown to directly bind to the

TLR2 Toll-like receptor 2 also known as TLR2 is a protein that in humans is encoded by the ''TLR2'' gene. TLR2 has also been designated as CD282 (cluster of differentiation 282). TLR2 is one of the toll-like receptors and plays a role in the immune sys ...

receptor, inhibiting downstream

signal transduction Signal transduction is the process by which a chemical or physical signal is transmitted through a cell as a series of molecular events, most commonly protein phosphorylation catalyzed by protein kinases, which ultimately results in a cellula ...

. It has also been studied that the inactivation of ESAT-6 leads to decreased virulence of ''M. Tuberculosis''. Secretion of the ESAT-6 protein is one of the main determining factors in the virulence of the ''M. Tuberculosis.'' ESAT-6 has more commonly become a marker for the TB diagnosis and treatment. There is also the use of the ESAT increase the production of virulent factors that cause for the increase in pathogenicity of TB. ESAT-6 is one of the main proteins that is inhibited in the production of vaccines for ''M. Tuberculosis'' with the combination of the increased antigenic factors agβ5-A and the agβ5-C. There are studies that are currently trying to connect the linkage between ESAT-6 and the epithelial cells that are in the lungs, which has shown the dependence on the induction of the IL-8 promoter.

ESAT-6 and CFP-10

There are also connections between the ESAT-6 marker and the CFP-10 marker. These are both being produced in ''

'' cells and is subject to the positive correlation of virulence to the amount of protein produced. Recent work shows that the production of these proteins is a process that is caused by the flanking genes. ESAT-6 and CFP-10 have also been increasingly used for in house antigen tests that now allow for quick testing of antibodies for the use of TB, but there are still determinations being made on what levels of these antigens or antibiodies would be considered normal. File:MTBVAC cell compared to Mycobacterium tuberculosis.png, The phoP and fadD26 rational inactivation in MTBVAC results in virulence attenuation and enhanced immunogenicity relative to the M. tuberculosis pathogen. File:Mycobacterium tuberculosis MEB (1).jpg, Microscope view of ''M. tuberculosis''

References

Tuberculosis Bacterial proteins {{actinobacteria-stub

ESAT-6 and CFP-10

See also

References