人類腸病毒A71型 (Human enterovirus A71, HEV-A71)隸屬於小RNA病毒科(Picornaviridae)、腸病毒屬 (Enterovirus)的病毒。主要感染五歲以下嬰幼兒，可以引發典型症狀手口足病、疱疹性咽峽炎以及感染中樞神經系統導致肢體麻痺症候群病毒性、腦炎，更嚴重會導致神經性肺水腫致死。腸病毒A71型感染需要辨識宿主表面的接受器，進一步進入宿主細胞。在實驗室先前的研究當中，使用糖蛋白質體的方法，找到有別於PSGL-1和SCARB2，會與EV-A71交互作用的糖蛋白「核仁蛋白」(nucleolin, NCL)。並且在細胞以及人類核仁蛋白基因轉殖鼠證實核仁蛋白能夠幫助腸病毒A71型進行感染。為了進一步了解人類核仁蛋白基因轉殖鼠受到病毒感染之後，產生後肢癱瘓的原因、感染後病程發展、組織受到病毒感染的情況是否跟核仁蛋白表現量相關、小鼠感染後體內的免疫表現，以及會出現的病徵，進行以下的實驗，並且藉此了解人類核仁蛋白基因轉殖鼠是否為一個適合用來研究腸病毒A71型的動物模式。在核仁蛋白表現量較高的基因轉殖鼠，其脊髓跟肌肉被病毒感染的程度較高；肌肉組織中的感染情形也較其他組織嚴重。基因轉殖鼠在感染後，體內IL-4, IL-6, IL-13, IL-1β, MCP1, IP-10, TNF-α表現量都比對照組來的高，代表免疫反應較為劇烈。且這些細胞激素在臨床上腸病毒A71病人感染後產生腦幹腦炎以及肺水腫有高度相關性。人類核仁蛋白基因轉殖鼠在感染腸病毒A71型/MP4病毒株之後，肺臟占體重的比例，與對照組相比，雖然沒有顯著差異，但是肺臟外觀較對照組紅腫，且部分基因轉殖鼠在顯微鏡下觀察到肺泡出血的現象，因此推測基因轉殖小鼠在感染後，可能有肺出血肺水腫的現象。 綜合以上，人類核仁蛋白基因轉殖鼠也許能夠在腸病毒A71型研究上面扮演一個很好的實驗模式，可以使用於未來基礎研究與腸病毒感染治療藥物及測試研究。

After the 1998 outbreak, enterovirus A71 (EV-A71) has become an endemic in Taiwan. EV-A71 infection is well known to cause hand-foot-mouth disease which may develop severe symptoms such as encephalitis, herpangina, paralysis, and lead to pulmonary edema even to death in children under 5 years old. The receptors for EV-A71, including scavenger receptor B2 (SCARB2), P-selectin glycoprotein ligand-1 (PSGL-1), annexin II, lactoferrin, and heparin sulfate, have been identified during the last decade. Although human SCARB2 and human PSGL-1 transgenic mice have also been developed, however, only few-day-old mice can be infected productively. Thus, a useful animal model for investigating EV-A71 pathogenesis in vivo is urgent. In the previous studies, we found a sialylated glycan gene human nucleolin (hNCL) that could promote virus binding and infection in vitro. After that, we wanted to demonstrate the EV-A71 pathogenesis in vivo. We found that MP4 (EV-A71 mouse adapted virus)-infected-hNCL transgenic mice displayed higher clinical scores and progressive limb paralysis prior to death. Based on the previous results, the immunologic characterization of cytokine responses to EV-A71 infection and pathogenesis in hNCL transgenic mice were investigated in this study. As the results of the tissue sections, we found that hNCL transgenic mice were more severely destroyed in thigh muscle and had highly EV-A71-VP1 signals in muscle, spinal cord, and brain stem comparing with C57BL/6 wild-type mice (WT mice); in the cytokine response, hNCL transgenic mice had higher IL-4, IL-6, IL-10, IL-13, IL-1β, MCP1, IP-10, TNF-α performances than WT mice. These cytokines were clinically related to encephalitis and pulmonary edema. The lungs of hNCL transgenic mice which were infected by the EV-A71 exhibited lightly swollen, redness and infiltration of erythrocytes in the alveoli under the microscopy. Next step, we will measure the neurotransmitters including epinephrine and norepinephrine and confirm whether this phenomenon is pulmonary edema. This novel animal model with these advantages may build a platform for basic and preclinical research in therapeutics in the future.

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