Transcription profiling of Mycobacterium bovis with pYUB412 and pRD1-2F9 genes knocked-in to investigate the ESX-1 secretion system

ABSTRACT: The dedicated secretion system ESX-1 of Mycobacterium tuberculosis encoded by the extended RD1 region (extRD1) assures export of the ESAT-6 protein and its partner, the 10 kDa culture filtrate protein CFP-10, and is missing from the vaccine strains M.bovis BCG and M.microti. Here, we systematically investigated the involvement of each individual ESX-1 gene in the secretion of both antigens, specific immunogenicity and virulence. ESX-1-complemented BCG and M.microti strains were more efficiently engulfed by bone marrow derived macrophages than controls and this may account for the enhanced in vivo growth of ESX-1 carrying strains. Inactivation of gene pe35 (Rv3872) impaired expression of CFP-10 and ESAT-6 suggesting a role in regulation. Genes Rv3868, Rv3869, Rv3870, Rv3871 and Rv3877 encoding an ATP-dependent chaperone and translocon were essential for secretion of ESAT-6 and CFP-10 in contrast to ppe68 (Rv3873) and Rv3876, whose inactivation did not impair secretion of ESAT-6. A strict correlation was found between ESAT-6 export and the generation of ESAT-6 specific T-cell responses in mice. Furthermore, ESAT-6 secretion and specific immunogenicity were almost always correlated with enhanced virulence in the SCID mouse model. Only loss of Rv3865 and part of Rv3866 did not affect ESAT-6 secretion or immunogenicity, but led to attenuation. This suggests that Rv3865/66 represent a new virulence factor that is independent from ESAT-6 secretion. This study has allowed us to identify new aspects of the extRD1 region of M.tuberculosis and to explore its role in the pathogenesis of tuberculosis. Data is also available from http://bugs.sgul.ac.uk/E-BUGS-31

ORGANISM(S): Mycobacterium bovis

SUBMITTER:  

PROVIDER: E-BUGS-31 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress