Department of Biology, Georgia State University, Atlanta, GA 30302, USA.
Virology. 2011 Mar 30;412(1):220-32. doi: 10.1016/j.virol.2011.01.008. Epub 2011 Feb 2.
Mosquito-borne flavivirus genomes contain conserved 5' and 3' cyclization sequences (CYC) that facilitate long distance RNA-RNA interactions. In previous studies, flavivirus replicon RNA replication was completely inhibited by single or multiple mismatching CYC nt substitutions. In the present study, full-length WNV genomes with one, two or three mismatching CYC substitutions showed reduced replication efficiencies but were viable and generated revertants with increased replication efficiency. Several different three adjacent mismatching CYC substitution mutant RNAs were rescued by a second site mutation that created an additional basepair (nts 147-10913) on the internal genomic side of the 5'-3' CYC. The finding that full-length genomes with up to three mismatching CYC mutations are viable and can be rescued by a single nt spontaneous mutation indicates that more than three adjacent CYC basepair substitutions would be required to increase the safety of vaccine genomes by creating mismatches in inter-genomic recombinants.
蚊媒黄病毒基因组包含保守的 5' 和 3' 环化序列 (CYC)，这些序列有利于长距离 RNA-RNA 相互作用。在以前的研究中，黄病毒复制子 RNA 的复制完全被单个或多个错配 CYCnt 取代所抑制。在本研究中，具有一个、两个或三个错配 CYC 取代的全长 WNV 基因组复制效率降低，但仍具有活力，并产生了复制效率增加的回复突变体。通过第二个点突变挽救了几种不同的三个相邻错配 CYC 取代突变 RNA，该突变在 5'-3' CYC 的内部基因组侧创建了一个额外的碱基对（nt147-10913）。全长基因组中最多有三个错配 CYC 突变是可行的，可以通过单个 nt 自发突变挽救，这表明需要更多的三个相邻的 CYC 碱基对取代，以通过在基因组间重组体中产生错配来提高疫苗基因组的安全性。
