Construction of a Nocardia seriolae knockout mutant lacking putative virulence genes and evaluation its potential as an attenuated live vaccine

2016 Fiscal Year Final Research Report

• Project/Area Number: 26850124
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Aquatic bioproduction science
• Research Institution: Kochi University
• Principal Investigator: Imajoh Masayuki 高知大学, 教育研究部自然科学系農学部門, 講師 (20565741)
• Project Period (FY): 2014-04-01 – 2017-03-31
• Keywords: Nocardia seriolae / ワクチン / ドラフトゲノム / ブリ / リアルタイムPCR法 / 体内動態 / 相同組換え法

Outline of Final Research Achievements

Nocardiosis caused by Nocardia seriolae is a major disease in cultured fishes of the genus Seriola in Japan. The whole genome sequence of the virulent strain N-2927 (NBRC 110360) and the non-virulent strain U-1 (NBRC 110359) was sequenced and annotated. The draft genome sequence of N-2927 has a total of 7,758,286 bp with a G+C content of 68.3%, and that of U-1 has a total of 7,766,019 bp with a G+C content of 68.3%. Mce gene, nocovactin biosynthesis gene, and polyketide synthase gene were identified as a candidate of pathogenic factor. Bath challenge of yellowtail Seriola quinqueradiata with strain N-2927 was mimic to natural exposure. An approach by using SYBR Green real-time PCR assay may be useful for in vivo evaluating vaccination effectiveness against nocardiosis in fish. A mce gene knockout strain of N. seriolae was made by homologous recombination, but the pathogenicity to yellowtail was not attenuated.

Free Research Field

魚病学