pUS933, a bifunctional fusion vector containing an amino-terminally truncated reporter gene, was constructed. Derivatives of pUS933, containing the promoter, RBS and start codon of the BCG gene, the 28 kDa gene and the 18 kDa gene were constructed and introduced into and BCG. β-Galactosidase activity was measured for mycobacteria grown in liquid culture. Primerextension analysis was used to determine the transcriptional start point for the 18 kDa promoter in Murine macrophages were infected with recombinant BCG containing the pUS933 derivatives and expression levels were examined, by fluorescence microscopy and fluorometry, during intracellular growth of BCG. Both the BCG gene promoter and the 28 kDa gene promoter gave high levels of β-galactosidase expression in all situations examined. In contrast, the M. leprae 18 kDa promoter fragment gave very low levels of expression in and BCG grown in liquid culture, but in BCG growing within macrophages it was induced to levels almost as high as the other promoters. This indicated that the 18 kDa gene is specifically activated during intracellular growth and may therefore be involved in survival of within macrophages. This pattern of regulation may be useful for controlling expression of foreign genes in recombinant BCG strains.


Article metrics loading...

Loading full text...

Full text loading...


Most cited this month

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error