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2012年7月,四川简阳市某养殖户水泥培育池的南方鲇(Silurus meridionalis)稚鱼发生了爆发性死亡,针对患病南方鲇稚鱼进行了寄生虫学、细菌学及病毒学鉴定。结果显示,病鱼鳃丝压片及体表粘液涂片在光学显微镜下未发现寄生虫。无菌操作分离得到2株优势菌,对其进行了形态学观察、生理生化鉴定、16S rDNA序列分析及系统进化树构建,结果表明,这两株细菌均为维氏气单胞菌(Aeromonas veronii)。动物回归感染试验表明其患病症状同自然发病症状,证明该菌为致病菌。14种常用药物敏感性试验结果显示,病菌对庆大霉素、多粘菌素B和美福仙敏感,对强力霉素、四环素、氟哌酸等10种药物不敏感。对病鱼组织匀浆攻毒试验和疑似病毒PCR检测,结果Ⅱ型疱疹病毒和蛙虹彩病毒特异性引物未能扩增出条带,仅斑点叉尾病毒orf 8引物扩增出157 bp大小的片段,且攻毒试验组鱼全部死亡,对照组鱼未死。因此确定该批爆发性死亡的南方鲇稚鱼感染斑点叉尾病毒。综上所述,此次爆发性死亡的南方鲇稚鱼病原经鉴定为斑点叉尾病毒和维氏气单胞菌。
In July 2012, an outbreak of juvenile juvenile Silurus meridionalis was carried out in a hydroponics pond of a farmer in Jianyang City, Sichuan Province. Parasitology, bacteriological and virological identification of juvenile juvenile fish were carried out. The results showed that gill filaments and superficial mucus smears did not find parasites under light microscopy. Two dominant bacteria were isolated by aseptic technique. Morphological observation, physiological and biochemical identification, 16S rDNA sequence analysis and phylogenetic tree construction were performed. The results showed that the two strains were Aeromonas veronii ). Animal regression test showed that the symptoms of the disease with the natural symptoms, the bacteria proved to be pathogenic bacteria. The results of 14 commonly used drug sensitivity tests showed that the bacteria were sensitive to gentamicin, polymyxin B and memantine, and insensitive to 10 drugs such as doxycycline, tetracycline and norfloxacin. The diseased fish tissue homogenate challenge test and the detection of suspected virus PCR, the results of the herpes simplex virus type II and iris virus-specific primers failed to amplify the band, only the point catfish ORF 8 primers amplified 157 bp size Fragments, and all the fish in the experimental group died, while the control group did not die. Therefore, it was confirmed that Southern juvenile fish of the batch of deaths were infected with the Pici. In summary, the outbreak of southern juvenile fish died pathogen identified as catfish and Vibrio aeruginosa.