The Study of Pathogenecity of Nervous Necrosis Virus (NNV) Isolated from Different Fish Species

不同魚類分離之魚類神經壞死症病毒病原性感染測試

廖睿雯(Rui-Wen Liao) ； 齊肖琪(Shou-Chi Chi)

《Acta Zoologica Taiwanica》 14卷2期 (2004/10) Pp. 125-126

https://doi.org/10.6576/AZT.2004.14.(2).18

摘要

NNV可引起三十幾種海水養殖魚大量死亡。本實驗在探討不同魚種NNV分離株對石斑魚的病原性有何差異。以來自海水的老鼠斑分離株(HGNNV)、淡水的中國鲶魚分離株(CCNNV)、冷水大西洋比目魚分離株(AHNNV)，對點帶石斑寸苗進行攻毒，結果HGNNV引起的死亡率是72%，CCNNV是29%，而AHNNV只有1%。經由PCR檢測，確定死亡魚隻體內都測到病毒，唯AHNNV的含量很低，故AHNNV可感染得上石斑魚，只是病毒複製量偏低，推測與病毒核酸複製最適溫度的差異有關。瀕死魚的腦及視網膜有嚴重空泡化現象，殘活魚則無，但測得到病毒，又免疫組織染色發現殘活魚視網膜附近的黑色素巨噬細胞中心有NNV存在。

關鍵字

神經壞死症病毒NNV ； 病原性 ； 空泡化 ； 視網膜

並列摘要

NNV has caused mass mortality in more than 30 fish species. The aim of this study is to investigate the pathogenecity of NNV isolated from different species of fish. The viruses used for immersion challenge test for grouper larvae include HGNNV isolated from hump-back grouper reared in sea water, CCNNV isolated from Chinese catfish reared in fresh water and AHNNV isolated from Atlantic halibut reared in cold water. The accumulated mortality of HGNNV was 72%, CCNNV was 29%, and AHNNV only 1%. The moribund grouper larvae were further examined by RT-PCR and semi-nested PCR, and NNV RNA was detected in the brain and retina of challenged fish. AHNNV was found to be able to infect grouper, although the level of AHNNV in the challenged grouper was very low. It is suggested that the low level of AHNNV in the challenged grouper is due to the improper temperature for viral RNA-dependent RNA polymerase. Vacuolation of brain and retina was only observed in the moribund fish but not in survivor fish. NNV was revealed in the brain and retina of survivor fish by immunohistochemistry (IHC) staining or immunofluorescent (IF) staining. In particular, it is the first time to find that NNV existed in the melanomacropahge center within the retina of survivor fish.

並列關鍵字

nervous necrosis virus NNV ； pathogenecity ； vacuolation ； retina