Engineered bacterial communication prevents Vibrio cholerae virulence in an infant mouse model

To investigate the possibility of using commensal bacteria as signal mediators for inhibiting the disease cholera, we stably transformed Escherichia coli Nissle 1917 (Nissle) to express the autoinducer molecule cholera autoinducer 1 (CAI-1) (shown previously to prevent virulence when present with another signaling molecule, autoinducer 2, at high concentrations) and determined the effect on Vibrio cholerae virulence gene expression and colonization in an infant mouse model. We found that pretreatment of mice for 8 h with Nissle engineered to express CAI-1 (Nissle-cqsA) greatly increased the mice's survival (92%) from ingestion of V. cholerae. Pretreatment with Nissle-cqsA for only 4 h increased survival by 77%, whereas ingesting Nissle-cqsA at the same time as V. cholerae increased survival rates by 27%. Immunostaining revealed an 80% reduction in cholera toxin binding to the intestines of mice pretreated for 8 h with Nissle-cqsA. Further, the numbers of V. cholerae in treated mouse intestines was reduced by 69% after 40 h. This finding points to an easily administered and inexpensive approach where commensal bacteria are engineered to communicate with invasive species and potentially prevent human disease.