Aichi Virus（AiV）為一種新興的人類致病性腸胃道病毒，在病毒基因體分類上屬於微小 RNA 病毒科（Picornaviridae）。AiV 感染所造成的臨床症狀主要有腹瀉、腹部疼痛、噁心反胃、嘔吐和發燒。高雄榮民總醫院於 2010 年確診出台灣首例感染 AiV 的幼兒病患，並以病毒增殖培養的方式分離出一株本土型的 AiV 病毒株。由於 AiV 是一新鑑別的微小 RNA 病毒，目前對於 AiV 感染之致病機轉以及其所誘發的先天性免疫反應了解甚少。因此本論文研究主要探討 AiV調控先天性免疫反應與其訊息傳導機制。我們發現此 AiV 本土株為一干擾素敏感型病毒株，interfern-α2 （IFN-α2）能有效抑制 AiV 的感染複製。即時定量聚合酶連鎖反應（real-time quantitative polymerase chain reaction, RT-qPCR）與 IFN-β（interferon-β）冷光報導基因分析（IFN-β luciferase reporter assay）的結果顯示，AiV 感染能誘發細胞表達輕微的 IFN-β 基因，並活化干擾素調控轉錄因子 Interferon Regulatory Factors 3 and 7 （IRF-3 與 IRF-7）。但在感染後期，我們發現 AiV 會水解切割 RIG-I （retinoic acid-inducible gene I）蛋白質，並因此減弱第一型干擾素的表達。我們推測此現象可能是 AiV 為了在細胞內進行有效的複製增殖所衍生的策略以負向回饋調控 type I IFN （type I interferon）的活性。本研究讓我們初步了解 AiV 感染所誘發之先天性免疫反應以及其調節機制，對於未來開發抗 AiV 病毒藥物或疫苗，提供了基本的病毒學理基礎。

Aichi virus (AiV) is a small, nonenveloped RNA virus categorized to Picornaviridae. AiV infection causes mild gastroenteritis, but in neonates, AiV usually causes the risk of certain enterovirus-related clinical syndromes, such as fever, nausea, vomiting and diarrhea. The first case of AiV infection in Taiwan was diagnosed from a young patient with diarrhea in Kaohsiung Veterans General Hospital, and the AiV was successfully isolated. Antiviral innate immune system of our body plays the major role to defense virus invasion. Because AiV is an emerging picornavirus, the knowledge about its pathogenesis and the interaction with host innate immunity were totally absent. This study aims to investigate the mechanism of AiV regulating innate immune response. We first demonstrated that AiV is a type I IFN sensitive virus. IFN-α2 treatment potently inhibited AiV replication. Real-time quantitative PCR data indicated that AiV induced only small amout of type I IFN gene expression, and the similar result was observed using IFN-β luciferase reporter assay. In addition, the AiV triggered IFN-β luciferase activity was progressively decreased in the late phase of infection. Immunoblotting assay showed that AiV evidently activated IRF-3 and IRF-7, the transcription factors of type I IFN induction. However, the retinoic acid inducible gene I (RIG-I) protein was cleavaged and its activity was downregulated by AiV. This data suggested that AiV triggered low level of type I IFN response may due to the negative feedback regulation of RIG-I activity. This immune evasion might be important for AiV replication in cells. Our study first reveals the status of innate immune response of AiV infection, and provides the basic virological theory for the development of anti-AiV drugs and vaccines in the future.

中文摘要 IV
英文摘要 VI
目錄 VII
圖次目錄 VIII
表次目錄 IX
壹、導論 1
一、Aichi virus 1
二、干擾素 2
三、RIG-I 4
貳、材料與方法 7
　　一、實驗材料 7
　　二、研究方法 10
參、結果 20
肆、討論 29
伍、圖次與圖次說明 32
陸、參考文獻 54
柒、附錄 59

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