[Purification and characterization of hec toxin produced by Aeromonas hydrophila]

An extracellular toxin produced by Aeromonas hydrophila from cultured crucian carp with septicemia was detected. The toxin was purified by ammonium sulfate precipitation, DEAE-cellulose chromatography and Sephadex G-100 gel filtration. The factor was a single polypeptide with a molecular weight of 52.5kd determined by SDS-PAGE. The heat-stable toxin possesses hemolytic, enterotoxic and cytolytic activities. The hemolytic activity on human erythrocytes was 3.81 x 10(3) HU/mg, CD50 for Vero cell was 0.26 microgram. The LD50 for crucian carp and mice was 4.44 micrograms and 3.58 micrograms respectively. The toxin was neutralized py homologous antibodies. The toxin shows unique characteristics as compared with other known bacterial toxins therefore the authors propose to name the toxin "hec" toxin.