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標題: | 模式辨識受體RIG-I 於神經壞死病毒感染中第一型干擾素之誘發角色 The retinoic acid-inducible gene I plays a major role in interferon induction during NNV infection |
作者: | Hsu-Yu Chen 陳叙伃 |
指導教授: | 吳金洌(Jen-Leih Wu) |
關鍵字: | 神經壞死病毒,先天免疫反應,干擾素,模式辨識受體,斑馬魚, nervous necrosis virus,innate immune response,interferon,Pathogen associated molecular Patterns receptors,zebrafish,Retinoic acid-inducible gene I, |
出版年 : | 2011 |
學位: | 碩士 |
摘要: | 第一型干擾素(Type I interferon)在先天免疫反應中扮演重要角色。其功能為在細胞受感染時能活化下游抗病毒蛋白,以抑制病毒之感染及複製。模式辨識受體(PAMPs receptors) 可偵測外來病原之特定核酸、蛋白或其它結構而啟動誘發IFN之訊息傳遞,被認為是先天免疫系統中之第一道防線。目前已知可辨識RNA病毒之PAMPs receptors包含: TLR3、TLR7、TLR22、MDA5及RIG-I。神經壞死病毒(nervous necrosis virus),為不含套模之RNA 病毒,主要感染魚類中樞神經系統,主要之天然宿主為重要之經濟物種石斑魚,近年來其感染造成台灣石斑養殖漁業重大損失。過去研究中以斑馬魚作為模式生物之研究發現,干擾素在 NNV致病機轉中扮演重要角色。實驗中,NNV 感染能誘發IFN 及下游抗病毒蛋白(Mx, p-eIF2α)之活化表現。然而,同樣抗免疫基因在感染之斑馬魚幼體中卻無法以RT-PCR偵測出,且感染造成幼魚高達90% 之死亡率。研究結果指出,IFN 之活化在對抗NNV 之感染中扮演關鍵性角色。然而,NNV 感染中之IFN 活化途徑及機制目前尚未清楚研究,因此,本研究之目的為: (1)探討NNV感染中IFN 之誘發機制。(2)此誘發路徑在斑馬魚不同發育階段之表現量差異。以分子機制之角度深入了解NNV之致病機轉及其在魚類發育早期所造成嚴重病變死亡之原因。
實驗中以斑馬魚之胚胎細胞株ZF-4做為感染模式,在細胞實驗中分析參與NNV 感染中IFN活化之模式辨識受體。實驗發現,位於細胞質中之模式辨識受體RIG-I可能在IFN的活化中扮演主要的角色。進一步研究中以反義核酸抑制細胞中RIG-I 基因表現,以證實其對啟動免疫反應之重要性。結果發現,RIG-I抑制後,細胞感染所誘發之IFN表現低於正常表現RIG-I之細胞約50倍。在RIG-I發育階段表現量之實驗中,亦初步證實成魚之基因表現量高於發育早期之幼魚約五倍。研究結果顯示RIG-I在NNV感染中為主要辨識病毒並活化免疫反應之模式辨識受體。 Type I Interferon (IFN), an important group of cytokine, can induce an antiviral state in most nucleated cells. In previous studies, we used zebrafish as a pathogenesis model and found that IFN response was involved in NNV infection. Nervous necrosis virus (NNV), a non-envelope virus which has bipartite genomes composed of two positive-sense RNAs, is a major fish pathogen that causes enormous loss for the aquaculture industry. NNV is known that it can causes acute infection and leads to high mortality in larvae, while causes persistent infection and leads to lower mortality in adult. Our previous research shows that the IFN system had been induced after infection in adult. However, IFN response in NNV infected larva was fail to be activated. Moreover, IFN pre-treatment in larva can rescue the mortality caused by NNV. This indicated that IFN induction plays a key role in protecting infected larvae. Several Pathogen associated molecular Patterns (PAMPs) receptors have been reported that can recognize virus RNA and trigger the IFN response. Our results show that cytosolic receptor RIG-I was highly activated after infection. Furthermore, its expression pattern was fit with the IFN induction. The knockdown experiments confirm the major role played by RIG-I in IFN induction upon NNV infection. At last, the RIG-I signaling in wild type larvae was much lower compare to the adult. Considering these result, we propose that IFN was mainly trigger by RIG-I signaling in NNV infection, and the insufficient expression of RIG-I causes weak IFN response and acute infection in larval fish. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/23774 |
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顯示於系所單位: | 漁業科學研究所 |
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