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Characterization of Aeromonas salmonicida and A. sobria isolated from cultured salmonid fish in Korea and development of a vaccine against furunculosis
Author(s) -
Lim Jongwon,
Hong Suhee
Publication year - 2020
Publication title -
journal of fish diseases
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.819
H-Index - 85
eISSN - 1365-2761
pISSN - 0140-7775
DOI - 10.1111/jfd.13158
Subject(s) - aeromonas salmonicida , biology , microbiology and biotechnology , rainbow trout , virulence , pathogenicity , antibiotics , bacteria , gene , fish <actinopterygii> , fishery , genetics
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 50 of 6.4 × 10 3 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.