Department of Marine Biotechnology, Gangneung-Wonju National University, Gangneung, Korea.
J Fish Dis. 2020 May;43(5):609-620. doi: 10.1111/jfd.13158. Epub 2020 Mar 20.
Previously, Aeromonas sobria and A. salmonicida were identified to be the most prevalent species in salmonid farms in Korea. In this study, we evaluated the biochemical characteristics, antibiotic susceptibility and pathogenicity of A. salmonicida (3 isolates) and A. sobria (8 isolates) isolated from salmonids, and further investigated efficacy of A. salmonicida vaccine. In antibiotic susceptibility test, all of A. sobria isolates were resistant to amoxicillin and ampicillin. Six A. sobria and two A. salmonicida isolates were resistant to oxytetracycline. In challenge test, A. sobria isolates exhibited low pathogenicity in rainbow trout (Oncorhynchus mykiss) while one A. salmonicida isolate showed high pathogenicity with LD of 6.4 × 10 CFU/fish in rainbow trout and coho salmon (Oncorhynchus kisutch). Among virulence factors, secretion apparatus (ascV and ascC) and transcription regulatory protein (exsA) of type 3 secretion system and A-layer protein genes were differentially detected in DNA or cDNA of A. salmonicida isolates, indicating their contribution to the pathogenicity. A formalin-killed vaccine of highly pathogenic A. salmonicida isolate exhibited a protective effect with relative survival rate of 81.8% and 82.9% at 8 weeks and 16 weeks post-vaccination, respectively, in challenge test.
先前，嗜水气单胞菌和鲑气单胞菌被鉴定为韩国鲑鱼养殖场最普遍的物种。在这项研究中，我们评估了从鲑鱼中分离出的鲑气单胞菌（3 株）和温和气单胞菌（8 株）的生化特性、抗生素敏感性和致病性，并进一步研究了鲑气单胞菌疫苗的效果。在抗生素敏感性测试中，所有温和气单胞菌分离株均对阿莫西林和氨苄西林具有抗性。6 株温和气单胞菌和 2 株鲑气单胞菌分离株对土霉素具有抗性。在攻毒试验中，温和气单胞菌分离株在虹鳟鱼（Oncorhynchus mykiss）中表现出低致病性，而 1 株鲑气单胞菌分离株在虹鳟鱼和银大麻哈鱼（Oncorhynchus kisutch）中表现出高致病性，LD 为 6.4×10 CFU/fish。在毒力因子方面，在鲑气单胞菌分离株的 DNA 或 cDNA 中差异检测到 III 型分泌系统的分泌装置（ascV 和 ascC）和转录调节蛋白（exsA）以及 A 层蛋白基因，表明它们对致病性的贡献。高致病性鲑气单胞菌分离株的福尔马林灭活疫苗在攻毒试验中表现出保护作用，攻毒后 8 周和 16 周的相对存活率分别为 81.8%和 82.9%。
