Can Non-Toxigenic Vibrio cholerae Reduce a Cholera Infection?

Vibrio cholerae, is the causative agent of cholera, that infects millions, annually. Chironomids are aquatic insects that host V. cholerae. Toxigenic strains produce cholera toxin (CT) which is the main virulence factor that causes cholera symptoms. In contrast to other bacterial pathogens, V. cholerae produces CT when at low cell densities while hemagglutinin/protease (HAP) is a high cell density-controlled gene. When V. cholerae behavior was examined on chironomids, we showed that high cell densities of non-toxigenic strains, increased HAP production in a toxigenic strain, conditions which could also potentially reduce CT production. Here we propose the value of studies that could support the potential of V. cholerae non-toxigenic strains to repress virulence gene expression in cholera-infected humans. High cell densities of a non-toxigenic strain present in an infected individual, may down-regulate CT expression, reducing cholera symptoms. To further test the hypothesis supported by a chironomid model, additional experiments in animal models are first needed.