泡沫病毒LTR研究进展.docVIP

 泡沫病毒 LTR 研究进展# 5 10 15 摘要：泡沫病毒(foamy virus，FV)属于逆转录病毒科，泡沫病毒属，为二聚线型 RNA 病毒， 是迄今发现的基因组最长的逆转录病毒(约 11～12kb)。与其他逆转录病毒相比，泡沫病毒具 有更复杂的基因结构，除了保守的结构基因 gag、pol 和 env，还有反式激活因子 Tas 以及存 在于长末端重复序列(long terminal repeat, LTR)的 P（promoter）和 env 3末端的 IP(internal promoter)两个启动子，这使得泡沫病毒基因的表达调控比其它逆转录病毒更为复杂。泡沫病 毒的 LTR 是逆转录病毒中最长的，不仅是病毒复制和整合所必需的，同时还具有启动子和 基因转录调控的功能。其 5’LTR 启动子是传统的反转录病毒启动子，包含 3 个部分即 U3 区、R 区和 U5 区。U3 区中有细胞和病毒转录因子结合区，病毒转录起始于 LTR 的 R 区， 而 R-U5 区存在负调控元件，能抑制其下游的基因的表达，此外 U5 区还存在着加帽位点 (capping site)和聚腺苷酸化信号(polyadenylation signal)，它们可形成特殊的茎环结构，被相 应的蛋白因子识别并结合。总之，LTR 对于病毒基因的转录调控具有重要作用。本文对 FV LTR 的结构及转录调节功能的研究进展进行了综述。 关键词：泡沫病毒；LTR；转录调控 中图分类号：R363 20 The research progress of foamy virus LTR DONG Lanlan, SHI Yingying, LIU Wanhong, HE Xiaohua (School of Basic Medical Sciences, Wuhan University,) Abstract: Foamy viruses (FVs), also known as spumaviruses or spumaretroviruses, are members 25 30 35 of the subfamily of Retroviridae. Compared to all other retroviral genera, FVs are more complex retroviruses; their genomes encode transcriptional protein Tas, in addition to the three conserved structure genes (gag, pol and env) and two promoters, which are the long terminal repeat (LTR) promoter and internal promoter (IP) in 3 end of env. And all those make the gene expression and regulation of FVs more complex. LTR of FVs is the longest among the retroviruses and is essential for integration, expression and regulation of the virus genome after infection. 5 LTR is the traditional promoter for retroviruses and it consist of U3 region, R region and U5 region. Major transcriptional regulatory elements are located in the U3 region, and the viral replication start from R region, and some negative regulatory elements (NRE) were identified in the U5 region as responsible for the downregulation of gene expression, in addition, U5 region also contains the capping site and polyadenylation signal, which can form the specific stem-loop structure and recognized by some factors. In a word, LTR pla