The vaccinia virus superoxide dismutase-like protein (A45R) is a virion component that is nonessential for virus replication
The vaccinia virus superoxide dismutase-like protein (A45R) is a virion component that is nonessential for virus replication
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DOI：
10.1128/jvi.75.15.7018-7029.2001
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发表时间：
2001-08-01
影响因子：
5.4
通讯作者：
Smith, GL
中科院分区：
文献类型：
--
作者：
Almazán, F;Tscharke, DC;Smith, GL
本文报道了牛痘病毒（VV）Western Reserve株A45 R基因的特征。该开放阅读框预计编码一个125个氨基酸的蛋白质（M-r，13，600），与铜锌超氧化物歧化酶具有39%的氨基酸同一性（Cu-Zn Son），本文和其他人对来自其他正痘病毒的A45 R基因进行测序，表明该蛋白在所有测序的病毒中高度保守，包括16株VV，2株牛痘病毒，骆驼痘病毒，和4株天花病毒。在所有情况下，蛋白质缺乏参与金属离子结合的关键残基，这对催化活性很重要。A45 R蛋白在大肠杆菌中表达，纯化，并测试Son活性，但既没有检测到酶活性也没有检测到抑制性SOD活性。此外，在感染的细胞或纯化的病毒体中没有检测到病毒编码的SOD活性。用抗A45 R蛋白的单克隆抗体鉴定A45 R基因产物为13.5kDa的蛋白，该蛋白在VV感染后期表达。VV感染细胞的共聚焦显微镜显示A45 R蛋白主要积聚在细胞质病毒工厂中。构建了缺失A45 R基因的大部分的缺失突变体和其中缺失的基因被恢复的回复突变体病毒，并进行了表征。缺失突变病毒的生长特性在所有检测的细胞系（包括巨噬细胞）中与野生型和回复突变病毒的生长特性没有区别。此外，三种病毒的毒力和致病性在鼠和兔感染模型中也相当，A45 R是第一个描述的既不影响病毒复制也不影响毒力的VV核心蛋白。
A characterization of the A45R gene from vaccinia virus (VV) strain Western Reserve is presented. The open reading frame is predicted to encode a 125-amino-acid protein (M-r, of 13,600) with 39% amino acid identity to copper-zinc superoxide dismutase (Cu-Zn Son), Sequencing of the A45R gene from other orthopoxviruses, here and by others, showed that the protein is highly conserved in all viruses sequenced, including 16 strains of VV, 2 strains of cowpox virus, camelpox virus, and 4 strains of variola virus. In all cases the protein lacks key residues involved in metal ion binding that are important for the catalytic activity, The A45R protein was expressed in Escherichia coli, purified, and tested for Son activity, but neither enzymatic nor inhibitory SOD activity was detected, Additionally, no virus-encoded SOD activity was detected in infected cells or purified virions. A monoclonal antibody raised against the A45R protein expressed in E, coli identified the A45R gene product as a 13.5-kDa protein that is expressed late during VV infection, Confocal microscopy of VV-infected cells indicated that the A45R protein accumulated predominantly in cytoplasmic viral factories, Electron microscopy and biochemical analyses showed that the A45R protein is incorporated into the virion core. A deletion mutant lacking the majority of the A45R gene and a revertant virus in which the deleted gene was restored were constructed and characterized. The growth properties of the deletion mutant virus were indistinguishable from those of wild-type and revertant viruses in all cell lines tested, including macrophages, Additionally, the virulence and pathogenicity of the three viruses were also comparable in murine and rabbit models of infection, A45R is unusual in being the first VV core protein described that affects neither virus replication nor virulence.