Expression, Purification, and Characterization of Hemolytic Toxin from Virulent Aeromonas hydrophila

Abstract Aeromonas hydrophila is a major pathogen in aquaculture in China; it is also an emerging pathogen in humans and animals. In recent years, several severe diseases, such as gastroenteritis, meningitis, and skin and soft tissue infections, have been found to be caused by A. hydrophila . Aerolysin and hemolysin are the most important virulence factors secreted by A. hydrophila . Therefore, new drugs targeted at these two toxins can be found in the therapy for A. hydrophila infections, reducing the usage of antibiotics. In this paper, we expressed and purified the aerolysin and hemolysin using a prokaryotic expression system. We found that aerolysin was more toxic than hemolysin, both in vitro and in vivo . The lethal dose ( LD 50 ) of aerolysin and hemolysin was 0.4 and 2.3 µg per fish, respectively.