Isshik T, Nishizawa T, Kobayashi T, Nagano T, Miyazaki T
Kagawa Prefectural Fisheries Experiment Station, Takamatsu, Japan.
Dis Aquat Organ. 2001 Nov 8;47(2):87-99. doi: 10.3354/dao047087.
A rhabdoviral disease occurred in farmed populations of market sized Japanese flounder (hirame) Paralichthys olivaceus in the Seto Inland Sea of Japan in 1996. The causative agent was identified as viral hemorrhagic septicemia virus (VHSV) based on morphological, immunological, and genetic analyses. Diseased fish that were artificially injected with a representative virus isolate showed the same pathological signs and high mortality as observed in the natural outbreak. This is the first report of an outbreak of VHSV infection in cultured fish in Japan. Clinical signs of diseased fish included dark body coloration, an expanded abdomen due to ascites, congested liver, splenomegaly, and a swollen kidney. Myocardial necrosis was most prominent and accompanied by inflammatory reactions. Necrotic lesions also occurred in the liver, spleen and hematopoietic tissue, and were accompanied by circulatory disturbances due to cardiac failure. Hemorrhagic lesions did not always appear in the lateral musculature. Transmission electron microscopy revealed many rhabdovirus particles and associated inclusion bodies containing nucleocapsids in the necrotized myocardium. The histopathological findings indicated that the necrotizing myocarditis could be considered a pathognomonic sign of VHSV infection in Japanese flounder.
1996年，日本濑户内海养殖的达到上市规格的牙鲆（hirame，即 Paralichthys olivaceus）群体中发生了一种弹状病毒病。基于形态学、免疫学和遗传学分析，致病因子被鉴定为病毒性出血性败血症病毒（VHSV）。人工注射代表性病毒分离株的患病鱼表现出与自然爆发中观察到的相同病理症状和高死亡率。这是日本养殖鱼类中VHSV感染爆发的首次报告。患病鱼的临床症状包括体色变黑、因腹水导致腹部膨胀、肝脏充血、脾肿大和肾脏肿大。心肌坏死最为突出，并伴有炎症反应。坏死病变也出现在肝脏、脾脏和造血组织中，并伴有因心力衰竭导致的循环障碍。侧肌中并不总是出现出血性病变。透射电子显微镜显示，在坏死的心肌中有许多弹状病毒颗粒以及含有核衣壳的相关包涵体。组织病理学结果表明，坏死性心肌炎可被视为牙鲆VHSV感染的特征性体征。
