ESAT-6 proteins: protective antigens and virulence factors?
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.
Unité de Génétique Moléculaire Bactérienne, Institut Pasteur, 28 rue du Docteur Roux, 75724 Paris Cedex, France.
Priscille
P
Brodin
Ida
I
Rosenkrands
Peter
P
Andersen
Stewart T
ST
Cole
Roland
R
Brosch
D000942:Antigens, Bacterial / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D009169:Mycobacterium tuberculosis / Q000276:immunology* / Q000472:pathogenicity*; D021381:Protein Transport; D014376:Tuberculosis / Q000175:diagnosis / Q000276:immunology / Q000382:microbiology / Q000517:prevention & control; D037521:Virulence Factors / Q000235:genetics / Q000276:immunology / Q000378:metabolism*
D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C093276:ESAT-6 protein, Mycobacterium tuberculosis; D037521:Virulence Factors