Functional analysis of the tick-borne encephalitis virus cyclization elements indicates major differences between mosquito-borne and tick-borne flaviviruses
Functional analysis of the tick-borne encephalitis virus cyclization elements indicates major differences between mosquito-borne and tick-borne flaviviruses
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DOI：
10.1128/jvi.80.8.4099-4113.2006
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发表时间：
2006-04-01
影响因子：
5.4
通讯作者：
Mandl, CW
中科院分区：
文献类型：
--
作者：
Kofler, RM;Hoenninger, VM;Mandl, CW
黄病毒的线性正链RNA基因组被认为是通过位于其末端区域的短互补序列元件的相互作用而形成环状构象。这种RNA环化过程是RNA复制的关键前提条件。对于蚊媒黄病毒，已经鉴定出高度保守的环化序列（CS），并且其功能已通过实验得到证实。在此，我们对蜱传脑炎病毒（TBEV）的CS元件进行了实验鉴定。这些元件被称为5'-CS - A和3'-CS - A，在各种蜱传黄病毒中是保守的，但它们与蚊媒CS元件无关，并且位于不同的基因组位置。5'-CS - A元件位于AUG起始密码子的上游而非下游，并且与蚊媒黄病毒相反，发现整个蛋白C编码区对TBEV复制不是必需的。互补的3'-CS - A元件位于底部茎环结构内而非特征性的3' - 末端茎环结构的上游，这意味着当基因组处于环状构象时，所提出的结构的这一部分无法形成。最后，我们证明当5'-CS - A元件从其天然位置移动到与蚊媒CS相对应的位置时，CS - A元件也能发挥其功能。对必需的RNA元件及其在蚊媒和蜱传黄病毒之间差异的认识，对疫苗和载体开发中的复制子设计具有实际意义。
The linear, positive-stranded RNA genome of flaviviruses is thought to adopt a circularized conformation via interactions of short complementary sequence elements located within its terminal regions. This process of RNA cyclization is a crucial precondition for RNA replication. In the case of mosquito-borne flaviviruses, highly conserved cyclization sequences (CS) have been identified, and their functionality has been experimentally confirmed. Here, we provide an experimental identification of CS elements of tick-borne encephalitis virus (TBEV). These elements, termed 5'-CS-A and 3'-CS-A, are conserved among various tick-borne flaviviruses, but they are unrelated to the mosquito-borne CS elements and are located at different genomic positions. The 5'-CS-A element is situated upstream rather than downstream of the AUG start codon and, in contrast to mosquito-borne flaviviruses, it was found that the entire protein C coding region is not essential for TBEV replication. The complementary 3'-CS-A element is located within the bottom stem rather than upstream of the characteristic 3'-terminal stem-loop structure, implying that this part of the proposed structure cannot be formed when the genome is in its circularized conformation. Finally, we demonstrate that the CS-A elements can also mediate their function when the 5'-CS-A element is moved from its natural position to one corresponding to the mosquito-borne CS. The recognition of essential RNA elements and their differences between mosquito-borne and tick-borne flaviviruses has practical implications for the design of replicons in vaccine and vector development.