Murine gammaherpesvirus 68 ORF35 is required for efficient lytic replication and latency
Murine gammaherpesvirus 68 ORF35 is required for efficient lytic replication and latency
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DOI：
10.1099/jgv.0.000310
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发表时间：
2015-12-01
影响因子：
3.8
通讯作者：
Ohno, Shinji
中科院分区：
文献类型：
--
作者：
Hikita, Shin-ichi;Yanagi, Yusuke;Ohno, Shinji
鼠γ疱疹病毒（MHV）68是田鼠的天然病原体，与人γ疱疹病毒、EB病毒（EBV;人疱疹病毒4）和卡波西肉瘤相关疱疹病毒（KSHV;人疱疹病毒8）相关。MHV-68的ORF 35与EBV、KSHV的同源基因均位于ORF 34-ORF 38组成的基因簇中，每个基因与相邻基因重叠。虽然MHV-68 ORF 35被报道为必需基因，但其在感染过程中的功能目前尚不清楚。在这项研究中，我们表明，通过分析ORF 35转染的细胞，在C末端的三个丝氨酸残基负责的磷酸化和ORF 35蛋白通过预测的卷曲螺旋基序形成同源寡聚体。通过转染表达的ORF 35蛋白优先位于未感染或感染MHV-68的细胞的细胞质中。缺乏ORF 35的重组病毒（35 S病毒）表现出与WT病毒相当的基因组复制和裂解蛋白的表达，但病毒产生水平降低，表明ORF 35蛋白在病毒体组装和/或排出步骤中起作用。鼻内感染后肺中的裂解复制和腹腔内感染后潜伏期的离体再激活频率在35 S病毒感染的小鼠中低于感染WT或标记回复病毒的小鼠。我们的研究结果表明，ORF 35是不是必不可少的MHV-68裂解复制，但在有效的病毒复制和重新激活从潜伏期起着重要的作用。
Murine gammaherpesvirus (MHV) 68, a natural pathogen of field mice, is related to human gammaherpesviruses, Epstein-Barr virus (EBV; human herpesvirus 4) and Kaposi's sarcoma-associated herpesvirus (KSHV; human herpesvirus 8). The ORF35 of MHV-68 and its homologues of EBV and KSHV are located in the gene cluster composed of ORF34-ORF38 in which each gene overlaps with adjacent genes. Although MHV-68 ORF35 was reported to be an essential gene, its function during infection is presently unknown. In this study, we show, by analysing ORF35-transfected cells, that three serine residues in the C terminus are responsible for the phosphorylation and that the ORF35 protein forms homo-oligomers via a predicted coiled-coil motif. The ORF35 protein expressed by transfection was preferentially located in the cytoplasm of cells uninfected or infected with MHV-68. The recombinant virus lacking ORF35 (35S virus) exhibited genome replication and expression of lytic proteins comparable to those of the WT virus, but reduced levels of virus production, suggesting that the ORF35 protein acts at the virion assembly and/or egress step. Lytic replication in the lung after intranasal infection and the frequency of ex vivo reactivation from latency after intraperitoneal infection were lower in 35S virus-infected mice than in mice infected with the WT or marker-reverted virus. Our results indicate that ORF35 is not essential for MHV-68 lytic replication, but plays an important role in efficient viral replication and reactivation from latency.