DAO 80:1-11 (2008)  -  doi:10.3354/dao01929

Histopathological and ultrastructural features of Koi herpesvirus (KHV)-infected carp Cyprinus carpio, and the morphology and morphogenesis of KHV

Teruo Miyazaki1,*, Yoshitaka Kuzuya1, Shinya Yasumoto1, Masahiro Yasuda1, Tatsuya Kobayashi2

1Graduate School of Bioresources, Mie University, 1577 Kurimamachiya-cho, Tsu, Mie 514-8507, Japan
2Fuji Biomedix, 10221 Kobitizawa, Hokuto, Yamanashi 408-0044, Japan

ABSTRACT: Epizootics of Koi herpesvirus (KHV) cause mass mortalities in koi carp and common carp worldwide. We used a newly developed ‘per-gill infection’ procedure with live KHV, and then conducted detailed histopathological and ultrastructural studies of KHV-infected cells including an examination of the morphology and morphogenesis of KHV. The primary target of KHV was respiratory epithelial cells of the gill lamellae, and release of virions from infected epithelial cells resulted in a systemic infection affecting the kidney, spleen, heart, brain and liver. The pathognomonic feature of infected cells was the formation of intranuclear inclusion bodies with marginal hyperchromatosis in the nucleus. Within the nucleus, assembly of capsids and nucleocapsids and an increase in filamentous nucleoproteins were evident. Enveloped nucleocapsids budded from the inner nuclear membrane into the perinuclear space. De-enveloped nucleocapsids were translocated in the cytoplasm to be embedded within inclusion bodies where tegumentation of the nucleocapsid occurred. Enveloped virions that had budded into intracytoplasmic vesicles and virions located extracellularly were composed of an electron-dense core, surrounded in turn by the capsid, the tegument and finally an envelope with projections. The morphology and morphogenesis of KHV were the same as those of viruses within the family Herpesviridae.


KEY WORDS: Koi herpesvirus · Koi · Common carp · Per-gill infection · Histopathology · Electron microscopy · Capsids · Nucleocapsids · Tegument · Virions


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Cite this article as: Miyazaki T, Kuzuya Y, Yasumoto S, Yasuda M, Kobayashi T (2008) Histopathological and ultrastructural features of Koi herpesvirus (KHV)-infected carp Cyprinus carpio, and the morphology and morphogenesis of KHV. Dis Aquat Org 80:1-11

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