Ribonucleases and bacterial virulence

Bacterial stress responses provide them the opportu-nity to survive hostile environments, proliferate and potentially cause diseases in humans and animals. The way in which pathogenic bacteria interact with host immune cells triggers a complicated series of events that include rapid genetic re-programming in response to the various host conditions encountered. Viewed in this light, the bacterial host-cell induced stress response (HCISR) is similar to any other well-characterized environmental stress to which bacteria must respond by upregulating a group of specific stress-responsive genes. Post stress, bacteria must resume their pre-stress genetic program, and, as a consequence, must degrade unnecessary stress responsive transcripts through RNA decay mecha-nisms. Further, there is a well-established role for several ribonucleases in the cold shock response whereby they modulate the changing transcript land-scape in response to the stress, and during acclima-tion and subsequent genetic re-programming post stress. Recently, ribonucleases have been implicated as virulence-associated factors in several notable Gram-negative pathogens including, the yersiniae, the salmonellae, Helicobacter pylori, Shigella flexneri and Aeromonas hydrophila. This review will focus on the roles played by ribonucleases in bacterial viru-lence, other bacterial stress responses, and on their novel therapeutic applications