Comparisons of Internal Behavior after Exposure to Flavobacterium psychrophilum between Two Ayu (Plecoglossus altivelis altivelis) Strains Showing Different Cumulative Mortality to Bacterial Cold Water Disease

Kageyama Tetsushi

Kuwada Tomonori

Ohara Kenichi

Nouno Aya

Umino Tetsuya

Furusawa Shuichi

Journal of Veterinary Medical Science

Bacterial cold water disease (BCWD) in ayu (Plecoglossus altivelis altivelis) has a serious impact on aquaculture and fisheries. There is known to be a significant difference among ayu strains with regard to mortality caused by BCWD. In this study, the immune response of different ayu strains against Flavobacterium psychrophilum infection was observed. One strain was resistant to infection by F. psychrophilum, and the other was susceptible to infection by the same bacteria. The number of bacteria in the body was observed in each ayu strain, and the change in bacterial counts was similar. However, there was a significant difference in bacterial count in the spleen between the two strains on days 6, 9, 12 and 15 after exposure. To observe the immune response against F. psychrophilum, agglutination assay using serum was performed. An agglutination reaction in the resistant ayu strain was observed in 4 out of 6 ayu on day 6 after exposure, while no reactions in the susceptible ayu strain were observed in any sampled fish until day 12. However, some reactions in the susceptible ayu strain were observed in surviving ayu. These results indicate that there is a correlation between the presence of bacterial multiplication and agglutination reaction against F. psychrophilum.

agglutination reaction

bacterial count

Flavobacterium psychrophilum

Plecoglossus altivelis altivelis

strain-dependent

畜産業 [ 640 ]

英語

The Japanese Society of Veterinary Science

公益社団法人日本獣医学会

Copyright (c) 2013 The Japanese Society of Veterinary Science

[ISSN] 1347-7439

[ISSN] 0916-7250

[NCID] AA10796138

[DOI] 10.1292/jvms.13-0047

[URI] https://www.jstage.jst.go.jp/article/jvms/75/12/75_13-0047/_article/