ISOLATION, PURIFICATION AND PATHOGENICITY OF THE HAEMOLYSIN PRODUCED BY AEROMONAS CAVIAE FROM SILURUS MERIDIONALIS CHEN
南方鲇(Silurus meridionalis)豚鼠气单胞菌溶血素的分离、纯化与致病性研究

The haemolysin produced by Aeromonas caviae was salted out by ammonium sulphate precipitation and purified by chromatography on Sephadex A50. It was estimated to a homogeneous polypeptide of 32.2kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Haemolysis assay showed that its haemolytic activity was 25. To investigate its pathogenicity, double dilution haemolysin was intraperitoneally injected into Silurus meridionalis Chen. The results showed that the purified haemolysin was toxic towards S. meridionalis, with a half-lethal dose (LD50) of 0.29mg/kg (protein/weight). Fish injected with this haemolysin exhibited symptoms of color fading, abdominal intumescence, congestion and enlargement of liver and spleen, renomegaly, gastrointestinal inflammation. Skeletal muscle appeared swollen and disruption with red stained sarcoplasm. Liver corroded to cell death and necrosis, and were congested with few sinusoid. Degeneration and necrosis was found in the renal cells, which could extend to some histolysis. Renal interstitium showed a reduced incidence of lymphocytes with numerous inflammatory cells infiltration. Spleen lymphocytes were reduction. The epithelial cells of gastrointestinal tract mucoa developed symptoms of degeneration, necrosis and desquamation.