A Novel sRNA in That Regulates Tolerance and Virulence Under Hyperosmotic Pressure.

Regulation of the environmental stress response and virulence of may involve multiple signaling pathways; however, these mechanisms are not well-defined. In bacteria, small regulatory RNAs (sRNAs) regulate bacterial growth, metabolism, virulence, and environmental stress response. Therefore, identifying novel functional sRNAs in could help elucidate pathogenic adaptations to host micro-environmental stresses and associated virulence. The aim of this study was to confirm the presence of an sRNA, , in and to determine its functions and possible mechanism of action. was found to regulate tolerance and virulence under hyperosmotic pressure. Its expression was verified by qRT-PCR and Northern blotting, and its genomic position was confirmed by 5'-rapid amplification of cDNA ends. expression was significantly decreased (~ 80%) under hyperosmotic conditions (680 mM NaCl), and the survival rate of the deletion strain increased by 20% under these conditions. This suggested that has been selected to promote host survival under hyperosmotic conditions. Additionally, virulence assessment, including guinea pig Sereny test and competitive invasion assays in mouse lungs, revealed that deletion significantly decreased virulence. Two-dimensional gel analyses suggest that may modulate the expression of , and genes, which may affect the virulence and survival of under osmotic pressures. Furthermore, expression has been shown to improve the survival of under osmotic pressures. These results suggest that has a broad range of action in response to hyperosmotic environmental stresses and in controlling its virulence to adapt to environmental stresses encountered during host infection.