Identification of 2',4'-Dihydroxychalcone as an Antivirulence Agent Targeting HlyU, a Master Virulence Regulator in .

The emergence of antimicrobial resistance and rapid acclimation allows to rapidly propagate in the host. This problematic pathological scenario can be circumvented by employing an antivirulence strategy, treating infections without hindering the bacterial growth. We developed a genome-integrated orthogonal inhibitor screening platform in to identify antivirulence agents targeting a master virulence regulator of . We identified 2′,4′-dihydroxychalcone (DHC) from the natural compound library and verified that it decreases the expression of the major toxin network which is equivalent to the ∆ deletion mutant. 2′,4′-DHC also reduced the hemolytic activity of which was tested as an example of virulence phenotype. The electrophoretic mobility shift assay confirmed that 2′,4′-DHC specifically targeted HlyU and inhibited its binding to P promoter. Under in vivo conditions, a single dose of 2′,4′-DHC protected ~50% wax-worm larvae from infection at a non-toxic concentration to both and wax-worm larvae. In the current study, we demonstrated that an orthogonal reporter system is suitable for the identification of antivirulence compounds with accuracy, and identified 2′,4′-DHC as a potent antivirulence agent that specifically targets the HlyU virulence transcriptional regulator and significantly reduces the virulence and infection potential of .