中文摘要：

复制转录激活蛋白（replication and transcription activator, RTA）是γ疱疹病毒的一个具序列保守性的蛋白质分子，由即时早期基因ORF50所编码．RTA可通过激活裂解期基凶转录而使病毒进入裂解感染．鼠疱疹病毒68（MHV-68）亦属γ疱惨病毒，该病毒能体外感染多种细胞，并且能感染实验小鼠，是研究叫疱疹病毒的良好模型．在MHV-68中，目前只有两个受RTA调控的基因被报道，但调控机制未明．之前的研究鉴定出一个新的RTA的DNA结合序列（RTA response element，RRE），以此为基础，首先通过基因比对在病毒基因组上找到具有较高同源性的核酸序列片段（ORF9p—RRE），该序列在病毒基因组上位于ORF9启动子区，通过双重荧光素酶报告基凶系统证实了RTA可作用于该启动子区进而激活下游基因转录，并且该转录激活是ORF9p-RRE依赖的．凝胶阻滞电泳实验（EMSA）和染色质免疫沉淀实验（ChIP）分别证实了RTA可在体外、体内与ORF9p—RRE直接结合．研究结果初步揭示了RTA与ORF9p—RRE相互作用的机制，为深入了解RTA激活病毒基因转录的机理提供了更多依据．

英文摘要：

Murine gammaherpesvirus-68 （MHV-68）, a close homologue of Epstein-Barr virus and Kaposi＇s sarcoma-associated herpesvirus, can infect many cell lines efficiently and is able to infect laboratory mice, and has emerged as an excellent model for studying its human counterparts. The replication and transcriptional activator （RTA）, mainly encoded by open read frame 50 （ORF50）, is a conserved immediate-early protein in gammaherpesviruses. RTA initiates the viral lytic cycle by activating the expression of downstream viral lytic genes. Therefore, it is important to investigate the mechanism by which RTA regulates downstream gene expression. Two RTA dependent promoters of MHV-68 had previously been reported, however, the mechanism of the interaction between RTA and the promoters was not characterized. Our group has previously identified a new RTA responsive element （named RRE-B） in MHV-68 and characterized in detail the mechanisms involved. In the study, we first analyzed the MHV-68 genome and identified a sequence homologous to RRE-B in the promoter region of OFR9, and designated it as ORF9p-RRE. Dual luciferase reporter assay showed that RTA could activate the ORF9 promoter and this activation was dependent on ORF9p-RRE. Electrophoretic mobility shift assay （EMSA） and chromatin immunoprecipitation assay （CHIP） further demonstrated that RTA bound to ORF9p-RRE in vitro and in vivo. In summary, we showed here that the promoter of MHV-68 ORF9 is responsive to RTA activation through ORF9p-RRE. The study provides support to further investigate and understand the role of RTA in regulating viral gene expression and viral life cycle.