Petrakova Olga, Volkova Eugenia, Gorchakov Rodion, Paessler Slobodan, Kinney Richard M, Frolov Ilya
Department of Microbiology and Immunology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-1019, USA.
J Virol. 2005 Jun;79(12):7597-608. doi: 10.1128/JVI.79.12.7597-7608.2005.
Venezuelan equine encephalitis (VEE) and eastern equine encephalitis (EEE) viruses are important, naturally emerging zoonotic viruses. They are significant human and equine pathogens which still pose a serious public health threat. Both VEE and EEE cause chronic infection in mosquitoes and persistent or chronic infection in mosquito-derived cell lines. In contrast, vertebrate hosts infected with either virus develop an acute infection with high-titer viremia and encephalitis, followed by host death or virus clearance by the immune system. Accordingly, EEE and VEE infection in vertebrate cell lines is highly cytopathic. To further understand the pathogenesis of alphaviruses on molecular and cellular levels, we designed EEE- and VEE-based replicons and investigated their replication and their ability to generate cytopathic effect (CPE) and to interfere with other viral infections. VEE and EEE replicons appeared to be less cytopathic than Sindbis virus-based constructs that we designed in our previous research and readily established persistent replication in BHK-21 cells. VEE replicons required additional mutations in the 5' untranslated region and nsP2 or nsP3 genes to further reduce cytopathicity and to become capable of persisting in cells with no defects in alpha/beta interferon production or signaling. The results indicated that alphaviruses strongly differ in virus-host cell interactions, and the ability to cause CPE in tissue culture does not necessarily correlate with pathogenesis and strongly depends on the sequence of viral nonstructural proteins.
委内瑞拉马脑炎（VEE）病毒和东部马脑炎（EEE）病毒是重要的自然出现的人畜共患病毒。它们是重要的人类和马病原体，仍然构成严重的公共卫生威胁。VEE和EEE病毒都能在蚊子中引起慢性感染，并在源自蚊子的细胞系中引起持续性或慢性感染。相比之下，感染这两种病毒的脊椎动物宿主会发生急性感染，伴有高滴度病毒血症和脑炎，随后宿主死亡或病毒被免疫系统清除。因此，EEE和VEE病毒在脊椎动物细胞系中的感染具有高度细胞病变性。为了在分子和细胞水平上进一步了解甲病毒的发病机制，我们设计了基于EEE和VEE的复制子，并研究了它们的复制情况以及产生细胞病变效应（CPE）和干扰其他病毒感染的能力。与我们之前研究中设计的基于辛德毕斯病毒的构建体相比，VEE和EEE复制子的细胞病变性似乎较小，并且能够在BHK-21细胞中轻易建立持续性复制。VEE复制子需要在5'非翻译区以及nsP2或nsP3基因中进行额外突变，以进一步降低细胞病变性，并能够在α/β干扰素产生或信号传导无缺陷的细胞中持续存在。结果表明，甲病毒在病毒-宿主细胞相互作用方面存在很大差异，并且在组织培养中引起CPE的能力不一定与发病机制相关，并且很大程度上取决于病毒非结构蛋白的序列。
