ESAT-6 proteins: protective antigens and virulence factors?

Trends Microbiol. 2004 Nov;12(11):500-8. doi: 10.1016/j.tim.2004.09.007.


The 6kDa early secreted antigenic target from Mycobacterium tuberculosis, ESAT-6, is the prototype of a novel family of small proteins of unknown function produced by Actinobacteria. Export of ESAT-6, a potent T-cell antigen, and related proteins requires a dedicated secretory apparatus that is encoded by a cluster of genes, several of which also code for proteins that are recognized strongly by T cells. ESAT-6 systems can thus be considered as immunogenicity islands and there is growing evidence that the corresponding genes are subject to selective pressure imposed by the immune system of the host. Recently, there has been major progress in understanding the biogenesis, secretion and antigenicity of ESAT-6 proteins and, at least in the case of ESAT-6 system 1, in unravelling their role in pathogenicity. Here, we discuss these findings and their implications for the development of new therapeutic and prophylactic interventions against tuberculosis.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Antigens, Bacterial / genetics
  • Antigens, Bacterial / immunology*
  • Antigens, Bacterial / metabolism*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / immunology
  • Bacterial Proteins / metabolism*
  • Humans
  • Mycobacterium tuberculosis / immunology*
  • Mycobacterium tuberculosis / pathogenicity*
  • Protein Transport
  • Tuberculosis / diagnosis
  • Tuberculosis / immunology
  • Tuberculosis / microbiology
  • Tuberculosis / prevention & control
  • Virulence Factors / genetics
  • Virulence Factors / immunology
  • Virulence Factors / metabolism*


  • Antigens, Bacterial
  • Bacterial Proteins
  • ESAT-6 protein, Mycobacterium tuberculosis
  • Virulence Factors