Vibrio cholerae requires rpoS for efficient intestinal colonization.

Area of Science:

• Microbiology
• Bacterial Pathogenesis
• Molecular Biology

Background:

• Vibrio cholerae is an intestinal pathogen found in aquatic environments.
• Vibrio cholerae causes diarrheal disease through intestinal colonization in animal models.
• The role of specific regulatory factors in V. cholerae colonization is not fully understood.

Purpose of the Study:

• To investigate the role of the alternative sigma factor RpoS in Vibrio cholerae intestinal colonization.
• To determine if RpoS is essential for V. cholerae pathogenesis in a suckling mouse model.

Main Methods:

• Construction of independent mutations within the rpoS gene.
• Assessment of V. cholerae colonization ability using competition assays in suckling mice.
• Evaluation of in vitro growth characteristics of mutant strains.
• Analysis of spontaneous suppressor mutations.
• Complementation of mutant phenotypes through trans-acting rpoS expression or allelic reversion.

Main Results:

• Multiple independent rpoS mutations resulted in a fivefold decrease in V. cholerae intestinal colonization.
• rpoS mutations did not affect in vitro growth in rich medium.
• Spontaneous suppressor mutations were ruled out as a confounding factor.
• Complementation studies confirmed that the reduced colonization was due to loss of functional RpoS.

Conclusions:

• The alternative sigma factor RpoS plays a significant role in Vibrio cholerae intestinal colonization.
• RpoS is essential for the colonization fitness of V. cholerae in the suckling mouse model.
• These findings identify RpoS as a key factor in V. cholerae pathogenesis.