Purification and characterization of an Aeromonas hydrophila hemolysin

A hemolysin produced by Aeromonas hydrophila CA-11, isolated from an environmental source, was purified by sulfopropyl-Sephadex C-25 chromatography at pH 5.0. This hemolysin caused fluid accumulation in infant mouse intestines and rabbit intestinal loops and killed Vero cells, as did the hemolysin produced by strain AH-1, isolated from a diarrheal case. In polyacrylamide gel electrophoreses at pHs 4.0 and 9.4 and in thin-layer isoelectric focusing, CA-11 hemolysin migrated as a single band to a position different from that of AH-1 hemolysin. Immunodiffusion tests indicated that CA-11 hemolysin was immunologically related to AH-1 hemolysin but possessed unique antigenic determinants. Neutralization tests with antihemolysin sera also demonstrated immunological cross-reactivity between AH-1 and CA-11 hemolysins. These results apparently indicate that the hemolysins produced by the two strains of A. hydrophila are immunologically and physicochemically different from each other.