Deng Hongyu, Chu Julia T, Park No-Hee, Sun Ren
Department of Molecular & Medical Pharmacology, Dental Research Intsitute, UCLA AIDS Institute, Jonsson Comprehensive Cancer Center, University of California at Los Angeles, Los Angeles 90095-1735, USA.
J Virol. 2004 Sep;78(17):9123-31. doi: 10.1128/JVI.78.17.9123-9131.2004.
Human gammaherpesviruses are associated with lymphomas and other malignancies. Murine gammaherpesvirus 68 (MHV-68) infection of mice has emerged as a model for understanding gammaherpesvirus pathogenesis in vivo. In contrast to human gammaherpesviruses, MHV-68 replicates in permissive cell lines in a robust manner, presenting an efficient model to study the basic mechanisms for DNA replication and recombination processes. In addition, MHV-68 also infects a broad range of cells of different tissue types and from different host species, and the viral genome persists as an episome in infected cells. These features make MHV-68 an attractive system on which to build gene delivery vectors. We have therefore undertaken a study to identify the cis elements required for MHV-68 genome replication and packaging. Here we report that an 8.4-kb MHV-68 genomic fragment between ORF66 and ORF73 conferred on the plasmid the ability to replicate; replication required the presence of either de novo viral infection or viral reactivation from latency. We further mapped the origin of lytic replication (oriLyt) to a 1.25-kb region. Moreover, we demonstrated that the terminal repeat of the viral genome is sufficient for packaging of the replicated oriLyt plasmid into mature viral particles. Functional identification of the MHV-68 oriLyt and packaging signal has laid a foundation for investigating the mechanisms controlling gammaherpesvirus DNA replication during the viral lytic phase and will also serve as a base on which to design gene delivery vectors.
人类γ疱疹病毒与淋巴瘤及其他恶性肿瘤相关。小鼠γ疱疹病毒68(MHV - 68)感染小鼠已成为了解γ疱疹病毒体内发病机制的模型。与人类γ疱疹病毒不同,MHV - 68能在允许的细胞系中高效复制,为研究DNA复制和重组过程的基本机制提供了一个有效的模型。此外,MHV - 68还能感染不同组织类型和不同宿主物种的多种细胞,并且病毒基因组以附加体的形式存在于受感染细胞中。这些特性使MHV - 68成为构建基因传递载体的一个有吸引力的系统。因此,我们开展了一项研究以确定MHV - 68基因组复制和包装所需的顺式元件。在此我们报告,位于开放阅读框66(ORF66)和开放阅读框73(ORF73)之间的一个8.4 kb的MHV - 68基因组片段赋予了质粒复制能力;复制需要有新的病毒感染或从潜伏状态重新激活病毒。我们进一步将裂解复制起点(oriLyt)定位到一个1.25 kb的区域。此外,我们证明病毒基因组的末端重复序列足以将复制的oriLyt质粒包装到成熟的病毒颗粒中。MHV - 68 oriLyt和包装信号的功能鉴定为研究病毒裂解期控制γ疱疹病毒DNA复制的机制奠定了基础,也将作为设计基因传递载体的基础。