摘要:
To study the pathogenicity of Yersinia ruckeri to rainbow trout (Oncorhynchus mykiss), this paper estab-lished a pathological model of enteric redmouth disease (ERM) and developed the corresponding scoring system of the clinical signs and histopathology. 43 healthy O. mykiss with the average weight of 12 g were randomly divided into 5 groups: three experimental groups (n=30) , control group (n=10)and sentinel group (n=3). The fish in three experimental groups were intraperitoneally injected withY. ruckeri at a concentration of 2.0×106, 2.0×107 and 2.0×108 CFU/mL, respectively. The clinical signs and pathological changes of intestine, liver, spleen and kidney in the infected fish were determined. Bacteriological test was also used to evaluate the effect of the infection model. The challenged fish presented different degrees of death in 72 h and showed some clinical signs such as red mouth, anal swelling, different degrees of congestion in fins (pectoral, pelvic, anal fins), obvious blood spots in lateral line and abdomen. Histopathology indicated that the infiltration, hyperemia and hemorrhage of cells in the liver, spleen, kidney and intestine were observed. Degeneration and necrosis were found in the liver cells, intestinal epithelial cells, renal tubular epithelial cells and other parenchymal cells. In spleen, the number of lymphocytes decreased and the red blood cells heaped up to death. The results showed that the best disease model could be constructed by Y. ruckeri at a concentration of 2.0×107 CFU/mL forO. mykiss and the clinical signs were significant with little differences and the disease was in a slow progress. The pathological model of the enteric red mouth disease was successfully established by intraperitoneal injection of 0.1 mLY. ruckeri at a concentration of 2.0×107 CFU/mL for O. mykiss juveniles with the body weight of about 12 g.%为探讨鲁氏耶尔森菌侵染虹鳟的致病机制,本实验建立了鲁氏耶尔森菌感染虹鳟引起的肠炎红嘴病的病理模型,制定相应的临床症状及组织病理学评分系统,并对该模型进行研究.将43尾平均体质量约为12 g的健康虹鳟随机分成5组:3个实验组(n=30)、对照组(n=10)和哨兵组(n=3).3个实验组分别采用2.0×106、2.0×107和2.0×108 CFU/mL的鲁氏耶尔森菌感染浓度,通过腹腔注射方式进行人工感染试验.对感染鲁氏耶尔森菌的虹鳟肠、肝脏、脾脏和肾脏组织进行镜检及临床症状、剖检病变判断,结合细菌学检测,按制定的评分系统评价各组肠炎红嘴病造模效果,确定最佳造模方案.结果显示,各攻毒组虹鳟感染后72 h均出现不同程度死亡,临床症状表现为红嘴、肛门红肿、鳍(胸鳍、腹鳍、臀鳍)等出现不同程度充血,下颌部、腹部出现出血点等.组织病理学可见肝脏、脾脏、肾脏及肠组织均有炎性细胞浸润现象出现,肝细胞、肠上皮细胞和肾小管上皮细胞等实质细胞变性、坏死,脾脏部位淋巴细胞减少、红细胞死亡堆积.综合各组得分发现,2.0×107 CFU/mL组的鲁氏耶尔森菌感染虹鳟造模效果最佳,患病虹鳟的临床症状显著且组内差异较小,病程迁延较长,便于研究.研究表明,对体质量约12 g的虹鳟幼鱼腹腔注射0.1 mL浓度为2.0×107 CFU/mL的鲁氏耶尔森菌可成功构建肠炎红嘴病病理模型.