Virus and Prion Diseases of Livestock Research Unit, National Animal Disease Center, USDA, Agricultural Research Service, Ames, IA 50010, USA.
Virology. 2012 Dec 5;434(1):38-42. doi: 10.1016/j.virol.2012.08.020. Epub 2012 Aug 29.
Porcine circovirus (PCV) has been assumed to replicate its genome via the rolling-circle replication (RCR) mechanism because it encodes a Rep protein that contains several amino acid motifs commonly found in other RCR biological systems. Two proteins, Rep and Rep', are essential for PCV DNA replication in mammalian cells. In this work, replicative intermediates of PCV-infected porcine kidney (PK15) cells or copy-release of PCV genomes from a head-to-tail tandem construct (without Rep') in Escherichia coli were examined. In PK15 cells, replicative intermediates consistent with complementary-strand replication which converts single-stranded circular genome to double-stranded supercoiled DNA and RCR which generates single-stranded plus strand progeny genome were observed. To a lesser extent, intermediates suggestive of recombination-dependent replication were also detected. In Escherichia coli, copy release of the single-stranded circular PCV genome with conversion to a supercoiled molecule by complementary-strand synthesis was observed. However, replicative intermediates indicative of RCR were not detected.
猪圆环病毒（PCV）被认为通过滚环复制（RCR）机制复制其基因组，因为它编码一种 Rep 蛋白，该蛋白含有几种常见于其他 RCR 生物系统的氨基酸基序。Rep 和 Rep' 两种蛋白对于哺乳动物细胞中 PCV DNA 的复制是必不可少的。在这项工作中，检测了感染猪肾（PK15）细胞的 PCV 或从串联头尾构建体（无 Rep'）释放 PCV 基因组的复制中间体。在 PK15 细胞中，观察到与互补链复制一致的复制中间体，该复制将单链环状基因组转化为双链超螺旋 DNA，而 RCR 则产生单链加链亲代基因组。在较小程度上，还检测到提示重组依赖性复制的中间体。在大肠杆菌中，观察到单链环状 PCV 基因组的拷贝释放，通过互补链合成转化为超螺旋分子。然而，没有检测到提示 RCR 的复制中间体。
