Studies on tissue-speciflc pathogenicity of picoronaviruses

Piconraviridae是一个大家族的正链RNA病毒。该科中每种病毒的致病性是相当不同的。如脊髓灰质炎病毒、柯萨奇病毒、甲型肝炎病毒、鼻病毒分别引起急性脑炎、心肌炎、肝炎和普通感冒。本研究的目的是阐明脊髓灰质炎病毒组织特异性致病的分子机制。1.人脊髓灰质炎病毒受体（PVR）基因转基因小鼠的制备。PVR被认为是宿主范围限制和组织嗜性的主要决定因素。为了确定PVR表达对组织嗜性的影响，我们已经产生了两种转基因小鼠，其中PVR以不同的分布模式表达。在hg-PVR小鼠模型中，PVR基因在其自身的启动子下表达，PVR仅分布于神经元而不分布于神经胶质细胞。在另一种，CAG PVR小鼠中，PVR普遍表达。脑内接种脊髓灰质炎病毒后，前者表现出类似于人类脊髓灰质炎的麻痹性疾病并死亡，而后者则存活而无麻痹。提示PVR表达模式在脊髓灰质炎病毒神经致病机制中的重要性。我们制备了脊髓灰质炎病毒和CVB 3病毒之间的嵌合病毒。具有CVB 3 5 '非编码区的脊髓灰质炎病毒嵌合体表现出与脊髓灰质炎病毒相似的神经致病性。具有脊髓灰质炎病毒5 ′-非编码区的CVB 3嵌合体不显示神经致病性。这些结果表明，各病毒编码区在组织特异性感染中的重要性。3.肠病毒71株感染性cDNA的构建。EV 71也是一种嗜神经性病毒，尚未进行广泛分析。我们已经构建了一个感染性的cDNA克隆的EV 71株，SK 006/马来西亚，这是从直肠拭子分离的病人死于致命的脑炎。该cDNA克隆为研究EV 71的嗜神经性提供了有力的工具。

Piconraviridae is a large family of positive-stranded RNA viruses. The pathogeniciy of each virus in this family is quite different. For example, poliovirus, coxsakievirus, hapatitis A virus, rhinovirus cause acute encephalitis, myocarditis, hepatitis and common cold, respectvely. Aim of our research is to elucidate molecular mechanism to determine tissue-specific pathogenicity of pjcoraaviruses.1.Production of transgenic mice expressing human poliovirus receptor (PVR) gene. PVR has been considered as a major determinant of host range restriction and tissue tropism. To determine the influence of PVR expression on the tissue tropism, we have produced two transgenic mice in which PVR is expressed with a different distribution pattern. In one model, hg-PVR mouse, PVR gene is expressed with its own promoter and PVRis distributed only in neurons but not glial cells. In the other, CAG-PVR mouse, PVRis expressed ubiquitously. After intracerebral inoculation of poliovirus, the former showed a paralytic disease that resembles human poliomyelitis and died, while the latter survived without paralysis. The results suggested importance of PVR expression patterns on neuropathogenesis of poliovirus.2.Pathogenicity of chmeric viruses. We produced chimeric viruses between poliovirus and CVB3 virus. A poliovirus chimera having 5'-noncoding region of CVB3 showed neuropathogenic property similar to poliovirus. A CVB3 chimera having 5'-noncoding region of poliovirus did not show neuropathogenic property. The results suggested the importance of coding region of each virus for the tissue-specific infection.3.Construction of Infectious cDNA for enteorhlrus (EV)71. EV71 is also a neurotropic virus, which is not analysed extensively. We have constructed an infectious cDNA clone for an EV71 strain, SK006/Malaysia, which was isolated from a rectal swab of a patient died of fatal encephalitis. This cDNAclone will be a powerful tool to investigate neurotropism of EV71.