Potential use of Sodium Butyrate (SB) as an anti-virulence agent against Vibrio cholerae targeting ToxT virulence protein.

Cholera, a diarrhoeal disease caused by gram-negative bacterium Vibrio cholerae remains a global health threat in developing countries owing to its high transmissibility and increase in antibiotic resistance. The current issue is to overcome the problem of resistance by antimicrobial therapy. There is a need for alternative strategies with an emphasis on anti-virulent approaches to alter the outcome of bacterial infections. Vibrio cholerae causes cholera by secreting virulence factors in the intestinal epithelial cells. Virulence factors help in cholera toxin production and colonisation during infection. Here, we show that sodium butyrate (SB), a small molecule, had no effect on bacterial viability but was effective in suppressing the virulence attributes of V. cholerae. The production of cholera toxin (CT) was downregulated in a standard V. cholerae El Tor strain and two clinical isolates when grown in presence of sodium butyrate. Analysis of mRNA and protein levels further demonstrated that sodium butyrate reduced the expression of the ToxT-dependent virulence genes like tcpA and ctxAB. DNA-protein interaction assays conducted at cellular (ChIP) and in in vitro conditions (EMSA) indicated that sodium butyrate weakens the binding between ToxT and its downstream promoter DNA, likely by blocking DNA binding. Furthermore, the efficacy of sodium butyrate was confirmed by showing its anti-virulence activity and tissue damage recovery in animal models. Collectively, these findings suggest that sodium butyrate (SB) has the potential to be developed as an anti-virulence agent against V. cholerae in place of conventional antibiotics or as an adjunctive therapy to combat cholera.