A Mortality Outbreak Associated with Multiple Infectious Hematopoietic Necrosis Virus Strains in a Rainbow Trout Rearing Facility in Japan

Chaw Su Thin; Aoi Nonaka; Yusuke Kiuchi; Gosuke Tsuboi; Suguru Hirabe; Ryota Shimizu; Masako Mitsui; Fumiaki Shirotori; Tomohiro Takeuchi; Motoki Shigekura; Hiroki Hoshikawa; Motokazu Kawanobe; Shigeru Ogawa; Mitsuru Furihata; Eisuke Nakamura; Tomohito Takikawa; Hajime Matsuyama; Megumi Matsumoto; Goshi Kato; Motohiko Sano

doi:10.3147/jsfp.61.110

Short Communications

A Mortality Outbreak Associated with Multiple Infectious Hematopoietic Necrosis Virus Strains in a Rainbow Trout Rearing Facility in Japan

Chaw Su Thin ^†, Aoi Nonaka ^†, Yusuke Kiuchi, Gosuke Tsuboi, Suguru Hirabe, Ryota Shimizu, Masako Mitsui, Fumiaki Shirotori, Tomohiro Takeuchi, Motoki Shigekura, Hiroki Hoshikawa, Motokazu Kawanobe, Shigeru Ogawa, Mitsuru Furihata, Eisuke Nakamura, Tomohito Takikawa, Hajime Matsuyama, Megumi Matsumoto, Goshi Kato, Motohiko Sano

Author information

Chaw Su Thin ^†
Tokyo University of Marine Science and Technology [Japan]
Aoi Nonaka ^†
Tokyo University of Marine Science and Technology [Japan]
Yusuke Kiuchi
Tokyo University of Marine Science and Technology [Japan]
Gosuke Tsuboi
Tokyo University of Marine Science and Technology [Japan]
Suguru Hirabe
Tokyo University of Marine Science and Technology [Japan]
Ryota Shimizu
Tokyo University of Marine Science and Technology [Japan]
Masako Mitsui
Tokyo University of Marine Science and Technology [Japan]
Fumiaki Shirotori
Nagano Prefectural Fisheries Experimental Station [Japan]
Tomohiro Takeuchi
Nagano Prefectural Fisheries Experimental Station [Japan]
Motoki Shigekura
Nagano Prefectural Fisheries Experimental Station [Japan]
Hiroki Hoshikawa
Nagano Prefectural Fisheries Experimental Station [Japan]
Motokazu Kawanobe
Nagano Prefectural Fisheries Experimental Station [Japan]
Shigeru Ogawa
Nagano Prefectural Fisheries Experimental Station [Japan]
Mitsuru Furihata
Nagano Prefectural Fisheries Experimental Station [Japan]
Eisuke Nakamura
Fuji Trout Hatchery, Shizuoka Prefectural Research Institute of Fishery and Ocean [Japan]
Tomohito Takikawa
Fuji Trout Hatchery, Shizuoka Prefectural Research Institute of Fishery and Ocean [Japan]
Hajime Matsuyama
Fuji Trout Hatchery, Shizuoka Prefectural Research Institute of Fishery and Ocean [Japan]
Megumi Matsumoto
Tokyo University of Marine Science and Technology [Japan]
Institute for Aquaculture Biotechnology (IAB), Tokyo University of Marine Science and Technology [Japan]
Goshi Kato
Tokyo University of Marine Science and Technology [Japan]
Institute for Aquaculture Biotechnology (IAB), Tokyo University of Marine Science and Technology [Japan]
Motohiko Sano Corresponding author
Tokyo University of Marine Science and Technology [Japan]
Institute for Aquaculture Biotechnology (IAB), Tokyo University of Marine Science and Technology [Japan]
Author contributions

†These authors contributed equally: Chaw Su Thin, Aoi Nonaka

Keywords: IHNV, rainbow trout, multiple virus infection, single-direction sequencing, epidemiology

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Supplementary material

2026 Volume 61 Issue 3 Pages 110-113

DOI https://doi.org/10.3147/jsfp.61.110

Details

Abstract

We developed a protocol for epidemiological analysis of infectious hematopoietic necrosis virus (IHNV) that includes virus isolation from dead fish using limiting dilution titration on EPC cells, followed by RT-PCR and sequencing targeting partial regions of the nucleocapsid protein and glycoprotein genes. Application of this protocol to a spontaneous IHN-associated outbreak in rainbow trout fry in 2019 revealed that multiple IHNV strains belonging to two lineages (Nagano and North Kanto) were involved and appeared to originate from two upstream farms. These findings suggest that IHN outbreaks in farms supplied with river water can involve the simultaneous circulation of multiple virus strains rather than simple transmission of a single strain within a fish population.

Corresponding author

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