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Enteropathogenicity of non-toxigenic Vibrio cholerae O1 for adult mice
M Moyenuddin1, K Wachsmuth, S H Richardson
1Laboratory of Biological Sciences, Georgia State University, Atlanta 30303.
Abstract:
The enteropathogenic potential of 32 Vibrio cholerae O1 isolates that do not produce cholera toxin was examined in the orally inoculated, sealed adult mouse model. Live cultures (2 x 10(10) cfu/ml) of 7/16 clinical and 6/16 environmental isolates produced a positive intestinal fluid accumulation (FA) ratio that reached near maximum at approximately 5 h post-inoculation. Colony hybridization did not detect genes for cholera toxin, Escherichia coli heat-labile and heat-stable toxins, or shiga-like toxins. FA activity did not correlate precisely with cytotoxic activities on Chinese hamster ovary (28/32 positive), Vero (29/32) or HeLa (25/32) cells. Certain clinical and environmental isolates of non-toxigenic V. cholerae O1 appear to be enteropathogenic for the mouse, providing evidence that they may have pathogenic potential for humans through an as yet undefined mechanism(s).
Insights
Certain non-toxigenic Vibrio cholerae O1 strains show enteropathogenic potential in mice. These findings suggest a possible, yet undefined, mechanism for human disease caused by these V. cholerae O1 isolates.
Area of Science:
- Microbiology
- Infectious Diseases
- Pathogenesis
Background:
- Vibrio cholerae O1 is a major cause of cholera.
- Cholera toxin is the primary virulence factor.
- Non-toxigenic V. cholerae O1 strains are often considered less pathogenic.
Purpose of the Study:
- To investigate the enteropathogenic potential of non-toxigenic Vibrio cholerae O1 isolates.
- To determine if these strains can cause disease in a relevant animal model.
- To explore potential virulence mechanisms beyond known toxins.
Main Methods:
- Oral inoculation of adult mice with live V. cholerae O1 cultures.
- Assessment of intestinal fluid accumulation (FA) as a measure of enteropathogenicity.
- Colony hybridization to detect genes for known bacterial toxins (cholera toxin, E. coli toxins, shiga-like toxins).
- Evaluation of cytotoxic effects on various cell lines (CHO, Vero, HeLa).
Main Results:
- 7/16 clinical and 6/16 environmental non-toxigenic V. cholerae O1 isolates induced significant intestinal fluid accumulation in mice.
- No genes for cholera toxin, E. coli heat-labile/heat-stable toxins, or shiga-like toxins were detected in these isolates.
- Fluid accumulation activity did not directly correlate with observed cytotoxic effects on Chinese hamster ovary, Vero, or HeLa cells.
Conclusions:
- Some non-toxigenic Vibrio cholerae O1 clinical and environmental isolates exhibit enteropathogenic properties in the mouse model.
- These findings indicate a potential pathogenic role for these strains in human infections.
- The mechanism(s) underlying the enteropathogenicity of these non-toxigenic V. cholerae O1 strains remain to be elucidated.