點帶石斑魚 (Epinephelus coioides)，是台灣最重要的經濟養殖魚類之ㄧ，石斑魚的幼魚受到神經壞死病毒 (nodavirus) 感染死亡的情形相當嚴重，但成魚則相對的沒那麼嚴重，因此點帶石斑的成魚體內似乎有一套有效的防禦機制對抗神經壞死病毒的感染。神經壞死病毒會進入魚體裡的細胞，解開成兩條單股、正股的 RNA，RNA 1 和 RNA 2。RNA 1 會轉譯成 RNA 聚合酶 (RNA-dependent RNA polymerase, RdRp)，轉移到粒線體的膜上擔任病毒複製的工作。而 RNA 2 轉譯成外殼蛋白 (coat protein)，保留在細胞質中而有些會積聚在核裡，RNA 2 所擔任的工作是組裝成病毒粒子 (virion)。石斑魚的抗病毒基因大量表現蛋白會直接結合神經壞死病毒，抑制神經壞死病毒的活性。細胞內免疫螢光實驗發現誘導石斑魚的抗病毒蛋白表現可以藉由結合或干擾經壞死病毒殻蛋白在魚細胞內的位置及分佈聚集。神經壞死病毒的殻蛋白可專一性與抗病毒蛋白之作用子區域結合。dsRNA poly[I:C] 誘導石斑魚的抗病毒蛋白表現抑制神經壞死病毒的感染，顯示誘導石斑魚的抗病毒蛋白表現抑制神經壞死病毒抗原的外殼蛋白的聚集和神經壞死病毒 RNA 聚合酶的功能，造成病毒顆粒量減少。在細胞感染後的早期階段，大量表現石斑魚的抗病毒蛋白仍對神經壞死病毒具抗性。在這個研究裡我們證實石斑魚的 抗病毒蛋白 (Mx protein) 在抑制神經壞死病毒的感染扮演重要的角色。

Grouper (Epinephelus coioides) is one of the most important economical fishes in Taiwan, but because virus infection in the adult red-spotted groupers has often been neglected, thus groupers should have an efficient defense system against the nodavirus, but at the same time the antigens of the nodavirus were also taken noticed of, since the groupers were easily infected by the virus at their juvenile and larvae stage. Nodavirus will enter the target cells and uncoil into two single stranded, positive sense RNAs, i.e. RNA 1 and RNA 2. RNA 1 has encoded RNA-dependent RNA polymerase which was found to be located on the mitochondrial membrane and is responsible for the virus replication. RNA 2 was found to encode the capsid protein that was found to be located in the cytoplasm and also accumulated in the nucleus, with a function of virion assembly. It has been previously found that an overexpression of grouper Mx was proclaimed as a negative regulator of nodavirus activity through direct interaction, such that grouper Mx induction expression might bind and perturb intracellular localization of coat protein. Deletion analysis of grouper Mx indicated that coat protein of nodavirus could bind to the effector domain of Mx. The presence of grouper Mx in dsRNA poly[I:C] interferon system inhibited nodavirus infection, which showed that overexpressing grouper Mx had an inhibitory effect on both coat protein and RdRp of nodavirus antigens, resulting in reducing levels of virus yields. This study demonstrated a key role of grouper Mx in cellular resistance to nodavirus infection.

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