The level of expression of tviA in the ompR mutant is nearly 10-fold lower than that in the wild type strain , suggesting that the expression of tviA in S. typhi is activated by OmpR at the early stage of osmotic-stress .
The result demonstrates that the expression of tviA is activated by OmpR .
: -LRB- 0123456789 OmpR also binds to the promoter of tviA to activate its transcription , and thus act as an activator of Vi antigen .