RpoS controls the Vibrio cholerae mucosal escape response

Area of Science:

• Microbiology
• Molecular Biology
• Pathogenesis

Background:

• Vibrio cholerae causes severe diarrhea by colonizing the small intestine.
• The later stages of V. cholerae infection, particularly bacterial detachment and dissemination, are poorly understood.

Purpose of the Study:

• To investigate the mechanisms and regulation of Vibrio cholerae detachment from the intestinal epithelium.
• To identify key factors involved in the late stages of V. cholerae infection, termed the "mucosal escape response."

Main Methods:

• Confocal microscopy of infected rabbit ileal loops.
• Quantitative in vivo localization assays.
• Gene expression profiling of bacteria isolated from ileal loop fluid and mucus.
• Analysis of RpoS and HapR mutant phenotypes in vitro and in vivo.

Main Results:

• A novel "mucosal escape response" was observed, where V. cholerae detaches from the epithelium 12 hours post-inoculation.
• This response is dependent on the stationary phase sigma factor RpoS and the regulator HapR.
• RpoS orchestrates the upregulation of chemotaxis and motility genes, flagellar production, and bacterial movement.
• RpoS-dependent regulation also appears to coincide with reduced cholera toxin expression, potentially modulating virulence.

Conclusions:

• The mucosal escape response is a regulated RpoS-dependent program activating bacterial motility for dissemination.
• This response may represent a transition phase for V. cholerae, preparing it for subsequent stages of infection or environmental survival.
• Understanding this process offers insights into V. cholerae pathogenesis and potential targets for intervention.