南方鲇源豚鼠气单胞菌胞外产物活性与致病性研究

Study on Activity and Pathogenicity of Extracellular Products of Aeromonas caviae Isolated from Silurus meriaionalis

采用琼脂扩散法测定了南方鲇源豚鼠气单胞菌胞外产物酶活性和溶血活性,同时对胞外产物的细胞毒性和其致病性进行了研究。结果显示:南方鲇源豚鼠气单胞菌胞外产物具有蛋白酶、脂酶、明胶酶和脲酶活性,但不具有淀粉酶和卵磷脂酶活性,具有很强的溶血活性和细胞毒性。肌肉注射感染发现,其对南方鲇有强致病性,其LD50为每千克鱼体重0.802 mg;注射后的南方鲇肌肉、心、肝、肾、脾、肠和胃等组织发生了严重组织病理变化,骨骼肌和心肌坏死断裂,炎症细胞浸润;肝脏严重空泡变性;肾小管上皮细胞变性、坏死、间质内大量炎症细胞浸润;脾充血、出血,淋巴细胞减少,胃肠黏膜上皮细胞变性、坏死、脱落。

The enzymatic activity and hemolytic activity of extracellular（ECP） products of Aeromonas caviae isolated from Silurus meriaionalis Chen were determined by agar diffusion method. The eytotoxicity and the pathogenicity of S. meriaionalis Chen which were injected intramuscularly with the extracellular products were studied. The results showed that the extracellular products had the ability to producted protease, lipase, gelatinase, urease, haemolysins and cytotoxins. At the same time, it displayed pathogenicity to S. meriaionalis Chen, with a LD50 value of 0. 802 mg/kg. After injected intramuscularly with the ECP, the experimental fish showed obvious histopathologieal changes： The skeletal muscle and cardiac muscle had necrosis, fragmentation and inflammatory cell infiltration; The hepatic cell had a serious vacuolar degenemouseion; The nephric tubule had degenemouseion, necrosis and inflammatory cell infiltration between interstitial substance; The spleen had splenemia, hemorrhage and lymphocytopenia; The intestinal mucosa had necrosis and felling down.