摘要
混养的异育银鲫和鲢鱼种大批死亡,为明确发病死亡的病原和组织损伤并提供相关的疾病防控措施,进行了病鱼肉眼和显微镜检查、细菌学检测、病毒学检测、组织病理和药敏试验研究。结果发现,除在患病鱼体表偶然发现有少量不会引起充血等症状的杯体虫和车轮虫外,未在体内外发现其他寄生虫和真菌类病原;通过细菌分离、人工回感试验、生理生化特性和16S r RNA基因序列分析,从患病异育银鲫和鲢分离到的致病菌株均为嗜水气单胞菌;根据异育银鲫和鲢病毒性疾病的现状,使用鲤疱疹病毒2型(Cyprinid herpesvirus 2,Cy HV-2)DNA聚合酶基因的特异性引物分别对自然发病的异育银鲫和鲢进行PCR检测,只有异育银鲫检测到Cy HV-2,分别用它们的除菌组织上清液进行人工感染试验,只有异育银鲫出现充血症状和死亡现象;由此得出嗜水气单胞菌是异育银鲫和鲢发病死亡的主要病原,Cy HV-2是异育银鲫混合感染的次要病原。患病鲢与患病异育银鲫呈现出类似的组织病理现象,又有一些各自特有的组织病理表现,单纯细菌感染的鲢轻度病变以细胞颗粒变性为主,坏死细胞以核溶解为主,细菌和病毒混合感染的异育银鲫肝脏轻度病变以细胞滴状玻璃样变的变性为主,坏死组织细胞以核固缩和核碎裂为主,在肾脏和脾脏出现染色质边集于核膜的肿大细胞核,主要组织器官出现从变性到坏死的病理变化过程,最终失去应有的功能而死亡。依据药敏试验结果,建议内服诺氟沙星和氟苯尼考等抗生素防治本病的嗜水气单胞菌感染,混合感染Cy HV-2的异育银鲫可以通过注射Cy HV-2疫苗和生态养殖的方法控制和减少该病毒病感染和发展。
A large number of Carassius auratus gibelio and Hypophthalmichthys molitrix young fishes died in the polyculture ponds. In order to ascertain the etiology, tissue injury and provide disease prevention and control measures, macroscopic and microscopic examinations, bacteriological detecting, virological detecting,histopathological observation and drug susceptibility test were operated on the diseased fish. The results showed that there were a few Apiosoma sp. and Trichodina sp. on the body surfaces of diseased fish, which would not cause death and the symptoms of hyperemia and hemorrhage. No other parasitical and fungal pathogens were found. Isolated strains from diseased fish were identified as A. hydrophila by their morphological observation,physiological and biochemical characteristics, and sequence analysis of the 16 S r RNA gene. According to the present situations of C. auratus gibelio and H. molitrix viral diseases, one pair of specific primer for PCR amplification of Cyprinid herpesvirus 2(Cy HV-2) DNA polymerase gene was used to detect Cy HV-2 in diseased fish. Cy HV-2 was detected only in diseased C. auratus gibelio. The aseptic supernatants of homogenated tissues from naturally diseased C. auratus gibelio and H. molitrix were respectively used for the artificial infections. Only the former caused healthy C. auratus gibelio to display the clinical sign of hyperemia and to die. It was concluded from the results that A. hydrophila was the main pathogen of diseased C. auratus gibelio and H. molitrix and Cy HV-2 was the secondary pathogen of the diseased C. auratus gibelio. There were similar histopathological changes in both of the diseased H. molitrix infected only with A. hydrophila and diseased C. auratus gibelio infected with mixed infections of A. hydrophila and Cy HV-2. There were specific histopathological changes in each kind of diseased fish. Granular degeneration of liver and kidney appeared in the mild pathologic lesions and the nuclei of necrotic cells were mainly karyolysis in diseased H. molitrix. Hyaline degeneration of liver appeared in the mild pathologic lesions, the nuclei of necrotic cells were mainly karyopyknosis and karyorrhexis and the hypertrophied cell nuclei with marginated chromatin appeared in the kidney and spleen in diseased C. auratus gibelio. The main organs lost their functions as the result of undergoing the pathological processes from degeneration to necrosis and both kinds of diseased fish died eventually. The results of antimicrobial susceptibility tests suggested that Norfloxacin and Florfenicol could be used to prevent and control A. hydrophila infection.Cy HV-2 vaccine and ecological farming methods could be used to prevent and reduce the viral infection and viral development in diseased C. auratus gibelio.
出处
《水产学报》
CAS
CSCD
北大核心
2016年第3期428-444,共17页
Journal of Fisheries of China
基金
水产动物遗传育种上海市协同创新中心(ZF1206)
上海市重点学科建设项目(Y1101)~~
关键词
异育银鲫
鲢
嗜水气单胞菌
鲤疱疹病毒2型
组织病理
Carassius auratus gibelio
Hypophthalmichthys molitrix
Aeromonas hydrophila
Cyprinid herpesvirus 2
histopathology