Upton Jason W, Speck Samuel H
Department of Microbiology and Immunology, Emory University School of Medicine, 1462 Clifton Road, Suite 429, Atlanta, GA 30322, USA.
J Virol. 2006 Dec;80(24):11946-59. doi: 10.1128/JVI.01722-06. Epub 2006 Sep 27.
Gamma-2 herpesviruses encode homologues of mammalian D-type cyclins (v-cyclins), which likely function to manipulate the cell cycle, thereby providing a cellular environment conducive to virus replication and/or reactivation from latency. We have previously shown that the v-cyclin of murine gammaherpesvirus 68 is an oncogene that binds and activates cellular cyclin-dependent kinases (CDKs) and is required for efficient reactivation from latency. To determine the contribution of v-cyclin-mediated cell cycle regulation to the viral life cycle, recombinant viruses in which specific point mutations (E133V or K104E) were introduced into the v-cyclin open reading frame were generated, resulting in the disruption of CDK binding and activation. While in vitro growth of these mutant viruses was unaffected, lytic replication in the lungs following low-dose intranasal inoculation was attenuated for both mutants deficient in CDK binding as well as virus in which the entire v-cyclin open reading frame was disrupted by the insertion of a translation termination codon. This replication defect was not apparent in spleens of mice following intraperitoneal inoculation, suggesting a cell type- and/or route-specific dependence on v-cyclin-CDK interactions during the acute phase of virus infection. Notably, although a v-cyclin-null virus was highly attenuated for reactivation from latency, the E133V v-cyclin CDK-binding mutant exhibited only a modest defect in virus reactivation from splenocytes, and neither the E133V nor K104E v-cyclin mutants were compromised in reactivation from peritoneal exudate cells. Taken together, these data suggest that lytic replication and reactivation in vivo are differentially regulated by CDK-dependent and CDK-independent functions of v-cyclin, respectively.
γ-2疱疹病毒编码哺乳动物D型细胞周期蛋白（v-细胞周期蛋白）的同源物，其可能发挥作用来操纵细胞周期，从而提供一个有利于病毒复制和/或从潜伏状态重新激活的细胞环境。我们之前已经表明，鼠γ疱疹病毒68的v-细胞周期蛋白是一种癌基因，它结合并激活细胞周期蛋白依赖性激酶（CDK），并且是从潜伏状态有效重新激活所必需的。为了确定v-细胞周期蛋白介导的细胞周期调控对病毒生命周期的贡献，我们构建了重组病毒，其中在v-细胞周期蛋白开放阅读框中引入了特定的点突变（E133V或K104E），导致CDK结合和激活的破坏。虽然这些突变病毒的体外生长不受影响，但低剂量鼻内接种后在肺部的裂解复制对于缺乏CDK结合的两个突变体以及整个v-细胞周期蛋白开放阅读框因插入翻译终止密码子而被破坏的病毒均减弱。这种复制缺陷在腹腔内接种小鼠的脾脏中不明显，这表明在病毒感染急性期对v-细胞周期蛋白 - CDK相互作用存在细胞类型和/或途径特异性依赖性。值得注意的是，尽管无v-细胞周期蛋白的病毒从潜伏状态重新激活的能力高度减弱，但E133V v-细胞周期蛋白CDK结合突变体在脾细胞病毒重新激活中仅表现出适度缺陷，并且E133V和K104E v-细胞周期蛋白突变体在腹膜渗出细胞重新激活中均未受损。综上所述，这些数据表明体内裂解复制和重新激活分别由v-细胞周期蛋白的CDK依赖性和CDK非依赖性功能差异调节。
