Abstract

Aeromonas hydrophila, an opportunistic aquatic pathogen widely spread in aquatic environments, is responsible for a number of infectious diseases in freshwater aquaculture. In addition,A. hydrophilacan transmit from diseased fish to humans and results in health problems. The occurrence of antibiotic-resistant bacterial strains restricts the application of antibiotics and is responsible for failure of the treatment. Moreover, residues of antibiotics in aquatic products often threaten the quality and safety. Therefore, alternative strategies are called to deal with infections caused by antibiotic-resistant bacteria. Aerolysin, one of the most important virulence factors ofA. hydrophila, is adopted as a unique anti-virulence target on the basis of the anti-virulence strategy to battling infections caused byA. hydrophila. Palmatine, an isoquinoline alkaloid from a variety of herbal medicines that showed no anti-A. hydrophilaactivity, could reduce hemolysis of the bacterium by decreasing aerolysin production. The results of the qPCR assay demonstrated that the transcription of theaerAgene was suppressed. Moreover, cell viability and in vivo study showed that palmatine treatment could decrease the pathogenicity ofA. hydrophilaboth in vitro and in vivo. In summary, palmatine is a leading compound againstA. hydrophila-associated infection in aquaculture by inhibiting the expression of aerolysin.Keywords:Aeromonas hydrophila;aerolysin;palmatine;anti-virulence;antibiotic resistance