Skalsky Rebecca L, Hu Jianhong, Renne Rolf
Department of Molecular Genetics and Microbiology, and Shands Cancer Center, University of Florida, 1613 Mowry Road, Gainesville, FL 32610-3633, USA.
J Virol. 2007 Sep;81(18):9825-37. doi: 10.1128/JVI.00842-07. Epub 2007 Jul 11.
Maintenance of Kaposi's sarcoma-associated herpesvirus (KSHV) episomes in latently infected cells is dependent on the latency-associated nuclear antigen (LANA). LANA binds to the viral terminal repeats (TR), leading to recruitment of cellular origin recognition complex proteins. Additionally, LANA tethers episomes to chromosomes via interactions with histones H2A and H2B (A. J. Barbera et al., Science 311:856-861, 2006). Despite these molecular details, less is known about how episomes are established after de novo infection. To address this, we measured short-term retention rates of green fluorescent protein-expressing replicons in proliferating lymphoid cells. In the absence of antibiotic selection, LANA significantly reduced the loss rate of TR-containing replicons. Additionally, we found that LANA can support long-term stability of KSHV replicons for more than 2 months under nonselective conditions. Analysis of cis elements within TR that confer episome replication and partitioning revealed that these activities can occur independently, and furthermore, both events contribute to episome stability. We found that replication-deficient plasmids containing LANA binding sites (LBS1/2) exhibited measurable retention rates in the presence of LANA. To confirm these observations, we uncoupled KSHV replication and partitioning by constructing hybrid origins containing the Epstein-Barr virus (EBV) dyad symmetry for plasmid replication and KSHV LBS1/2. We demonstrate that multiple LBS1/2 function in a manner analogous to that of the EBV family of repeats by forming an array of LANA binding sites for partitioning of KSHV genomes. Our data suggest that the efficiency with which KSHV establishes latency is dependent on multiple LANA activities, which stabilize viral genomes early after de novo infection.
卡波西肉瘤相关疱疹病毒(KSHV)附加体在潜伏感染细胞中的维持依赖于潜伏相关核抗原(LANA)。LANA与病毒末端重复序列(TR)结合,导致细胞源识别复合物蛋白的募集。此外,LANA通过与组蛋白H2A和H2B相互作用将附加体 tether 到染色体上(A. J. Barbera等人,《科学》311:856 - 861,2006)。尽管有这些分子细节,但对于从头感染后附加体如何建立了解较少。为了解决这个问题,我们测量了增殖淋巴细胞中表达绿色荧光蛋白的复制子的短期保留率。在没有抗生素选择的情况下,LANA显著降低了含TR复制子的丢失率。此外,我们发现LANA可以在非选择性条件下支持KSHV复制子长达2个月以上的长期稳定性。对赋予附加体复制和分配功能的TR内顺式元件的分析表明,这些活动可以独立发生,而且这两个事件都有助于附加体的稳定性。我们发现含有LANA结合位点(LBS1/2)的复制缺陷型质粒在存在LANA的情况下表现出可测量的保留率。为了证实这些观察结果,我们通过构建包含爱泼斯坦 - 巴尔病毒(EBV)二元对称用于质粒复制和KSHV LBS1/2的杂交起源来解偶联KSHV复制和分配。我们证明多个LBS1/2以类似于EBV重复序列家族的方式发挥作用,通过形成一系列LANA结合位点来分配KSHV基因组。我们的数据表明,KSHV建立潜伏的效率取决于多种LANA活动,这些活动在从头感染后早期稳定病毒基因组。