• Korean Journal of Poultry Science
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• v.38 no.1
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• pp.13-19
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• 2011

In January 2010, high mortalities of ducklings occurred in two adjacent farms. Ducklings in farm A showed neurologic signs including paddling, opisthotonus and lameness, but ducklings from farm B had no specific clinical signs. At post mortem, diffused hemorrhagic spots in the liver and hemorrhages in the small intestine were observed in ducklings from farm A, and ducklings from farm B had only proventricular ulceration. Microscopically, multiple necrosis of hepatocytes, hyperplasia of the bile ducts, hemorrhages, infiltration of lymphocytes and bacterial colonies were commonly observed in the liver of ducklings from both farms. Also, type A and C duck hepatitis virus (DHV) were isolated from farm A and farm B, respectively and Salmonella typhimurium was commonly isolated and identified serologically and biochemically. To our knowledge, this is the first report about the co-infection of DHV and Salmonella typhimurium in ducklings, and co-circulation of type A and C duck hepatitis viruses in Korea.

• Journal of Life Science
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• v.25 no.2
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• pp.214-222
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• 2015

Aeromonas hydrophila is the most common water fish pathogen and cause diseases such as hemorrhagic septicemia, dropsy, ulceration and asymptomatic septicemia. A. hydrophila secretes many extracellular products (ECPs) which contribute to effective infection, wide distribution and great adaptability to environmental changes. Crude ECPs of A. hydrophila CK257, a strain used in this study, exhibits a toxic activity to the animals including mouse, rabbit and fish. Toxic symptoms were indicated by tissue damage and skin injuries in animal. When ECPs were subcutaneously injected to animals, skin damages were observed, appearing like necrosis. Preliminary research demonstrated that the active factors are protein component. The crude ECPs were collected after ammonium sulfate precipitation of cell-free culture supernatant. ECPs were fractionated with the use gel filtration chromatography. Five ECP fractions were obtained, of which one fraction was found to be toxic to goldfish. MALDI-TOF analyses provided two interesting proteases called M35 and M28. Both M35 and M28 are known as metalloprotease. Accordingly, proteins in an active fraction exhibited caseinolytic activity. These proteins were difference of caseinolytic activity under different metallic ions. Also active fraction has elastolytic activity. These results suggested that peptidase M28 and M35 may be a candidate factor for tissue necrosis activity about infection with A. hydrophila.