Quantifying Vibrio cholerae Enterotoxicity in a Zebrafish Infection Model.

Area of Science:

• Microbiology and Infectious Diseases
• Aquatic Animal Models
• Bacterial Pathogenesis

Background:

• Vibrio cholerae causes cholera, a diarrheal disease transmitted via contaminated food/water, particularly in areas with poor sanitation.
• V. cholerae inhabits aquatic environments and can colonize fish, suggesting a role for fish as environmental reservoirs.
• Zebrafish have been established as a novel model for studying V. cholerae intestinal colonization, pathogenesis, and transmission.

Purpose of the Study:

• To investigate the hypothesis that accessory toxins, not cholera toxin, cause diarrhea in V. cholerae-infected zebrafish.
• To develop and validate methods for quantifying diarrheal volume in zebrafish as a measure of V. cholerae pathogenesis.
• To identify specific accessory toxins contributing to diarrhea and understand their role in V. cholerae environmental transmission.

Main Methods:

• Adaptation of cell density, protein, and mucin assays to quantify diarrheal volume in zebrafish.
• Enumeration of V. cholerae within the zebrafish intestinal tract.
• Quantification of V. cholerae in the surrounding infection water.

Main Results:

• Zebrafish experimentally infected with V. cholerae exhibited diarrhea as early as 6 hours post-exposure.
• The developed assays enabled the quantification of diarrheal volume, serving as a metric for pathogenesis.
• These methods facilitate the assessment of accessory toxin effects on diarrheal volume in the zebrafish model.

Conclusions:

• Identifying accessory toxins causing diarrhea in zebrafish can elucidate the role of fish in V. cholerae environmental reservoirs.
• Accessory toxins may prolong V. cholerae colonization and shedding, enhancing environmental transmission and perpetuating outbreaks.
• These toxins might maintain low-level fish colonization, aiding V. cholerae survival when aquatic conditions are suboptimal.