江苏盐城地区异育银鲫大红鳃疾病病原学研究及病理学观察

为鉴定近期江苏盐城地区养殖异育银鲫大红鳃疾病病原，研究从患病濒死鱼中分离到两株致病菌并对其理化特性、分子生物学、感染病理学进行了研究，同时开展了鉴别诊断和回归试验以及药敏检测。结果显示，两分离株理化特性与温和气单胞菌（A.sobria）特征相符，与GenBank中A.sobria的gyrB基因同源性达99%以上，在系统发育树上均与A.sobria聚为一族。同时与鲤科疱疹病毒2型（CyHV-2）鉴别诊断结果表明，患病鱼组织中CyHV-2检测为阴性。组织学上，鳃和肾组织具有典型病理变化。人工感染两株A.sobria后，鱼体出现与自然发病相似的大红鳃症状，并能从发病鱼组织中再分离到相同病原菌；而人工感染CyHV-2组织匀浆后的鲫虽然出现死亡，但无大红鳃症状出现。综上，确认此次大红鳃疾病的病原为A.sobria。药敏实验表明，分离菌株对诺氟沙星、氧氟沙星、氯霉素三种药物敏感。研究为临床上更好的预防异育银鲫大红鳃疾病奠定了基础。

ETIOLOGY INVESTIGATION AND HISTOPATHOLOGICAL STUDY ON "RED-GILL" OF SILVER PRUSSIAN CARP (CARASSIUS AURATUS GIBELIO) IN YANCHENG CITY

Two Aeromonas sobria isolates, isolated from cultured Carassius auratus gibelio during an outbreak of mass mortality in Yancheng city of China, were identified to the species level by phylogenetic analysis based on gyrB gene and biochemical tests. The isolates were identified to be the pathogeny of Red-Gill through investigating for the virulence of bacteria by recurrent tests and histopathology. We also described the macroscopic and microscopic lesions in Carassius auratus gibelio naturally infected with A. sobria. Our findings confirmed that the 2 isolates, rather than cyprinid herpesvirus 2, were the primary pathogen of Red-Gill disease and damaged the immune system in Carassius auratus gibelio. The results of drug sensitivity tests showed that the bacterial isolates was sensitive to ofloxacin, chloromycetin and norfloxacin; While, resistant to oxacillin, vancomycin, ampicillin, penicillin, clindamycin etc. Together, our findings demonstrate the pathogenesis of Aeromonas sobria in Carassius auratus gibelio and establish the foundation for Red-Gill in cultured Carassius auratus gibelio.