Wu Y, Carstens E B
Department of Microbiology and Immunology, Queen's University, Kingston, Ontario, Canada.
J Virol. 1996 Oct;70(10):6967-72. doi: 10.1128/JVI.70.10.6967-6972.1996.
From the results of transient plasmid-based replication assays, it has been postulated that homologous regions (hrs) of Autographa californica nuclear polyhedrosis virus (AcMNPV) function as origins of viral DNA replication. However, these assays vary in specificity according to the methodology used and may not be dependent solely on the presence of hr sequences. To determine the role that hrs and other sequences might play in the replication process, a series of plasmids containing specific deletions of various hrs was generated and tested in a standardized replication assay. Deletion of the AcMNPV hr2 and hr5 sequences abolished the ability of plasmids to replicate in the standard infection-dependent replication assay, while deletion of hr1, hr3, and hr4a sequences decreased but did not eliminate plasmid replication in this assay. Plasmids carrying the complete ie-2 and pe38 genes, the ie-1 gene upstream region, or a variety of baculovirus genes including 11 early promoter regions were also able to replicate in virus-infected cells, suggesting that early viral promoter sequences could also function as putative origins of replication. These data suggest that the standard infection-dependent replication assay may identify a broad range of infection-dependent replicating sequences, only one or a few of which may represent genuine viral origins used by the virus in vivo. We propose a model suggesting that the selection of replication initiation sites may be imposed directly by chromatin structure and indirectly by primary sequence and that the process of viral DNA replication may be linked with viral transcription.
基于瞬时质粒的复制分析结果推测，苜蓿银纹夜蛾核型多角体病毒（AcMNPV）的同源区域（hrs）作为病毒DNA复制的起始点发挥作用。然而，这些分析根据所使用的方法在特异性上存在差异，并且可能不仅仅取决于hr序列的存在。为了确定hrs和其他序列在复制过程中可能发挥的作用，构建了一系列包含各种hrs特定缺失的质粒，并在标准化复制分析中进行测试。在标准的依赖感染的复制分析中，AcMNPV的hr2和hr5序列缺失消除了质粒的复制能力，而hr1、hr3和hr4a序列缺失降低了但并未消除该分析中质粒的复制。携带完整ie - 2和pe38基因、ie - 1基因上游区域或包括11个早期启动子区域在内的多种杆状病毒基因的质粒也能够在病毒感染的细胞中复制，这表明早期病毒启动子序列也可能作为假定的复制起始点发挥作用。这些数据表明，标准的依赖感染的复制分析可能鉴定出广泛的依赖感染的复制序列，其中只有一个或几个可能代表病毒在体内使用的真正病毒起始点。我们提出一个模型，表明复制起始位点的选择可能直接由染色质结构决定，间接由一级序列决定，并且病毒DNA复制过程可能与病毒转录相关联。
