College of Veterinary Medicine, Qingdao Agricultural University, Qingdao, 266109, China.
College of Veterinary Medicine, Qingdao Agricultural University, Qingdao, 266109, China.
Virology. 2021 Nov;563:126-133. doi: 10.1016/j.virol.2021.09.002. Epub 2021 Sep 9.
The 5' untranslated region (UTR) of Senecavirus A (SVA) harbors an internal ribosome entry site (IRES), in which a pseudoknot structure is upstream of start codon AUG. Wild-type SVAs have a highly conserved 13-nt-sequence between the pseudoknot stem II (PKS-II)-forming motif and the AUG. In this study, a single nucleotide was deleted one by one from the 13-nt-sequence within a wild-type SVA minigenome. The result showed that neither mono- nor multi-nucleotide deletions abolished the IRES activity. Furthermore, a single nucleotide was deleted one by one from the 13-nt-sequence within a full-length SVA cDNA clone. The result indicated that nucleotide-deleting SVAs could be rescued from 1- to 5-nt-deleting cDNA clones, whereas only the 1- and 2-nt-deleting viruses were genetically stable during nine serial passages in vitro. Additionally, only the 1-nt-deleting SVA showed similar growth kinetics to that of the wild-type virus, suggesting that the pseudoknot-AUG distance was crucial for SVA replication.
塞尼卡病毒 A（SVA）的 5'非翻译区（UTR）含有内部核糖体进入位点（IRES），在起始密码子 AUG 的上游存在假结结构。野生型 SVA 在假结茎 II（PKS-II）形成基序和 AUG 之间具有高度保守的 13-nt 序列。在这项研究中，从野生型 SVA 小基因组内的 13-nt 序列中逐个删除一个核苷酸。结果表明，单核苷酸或多核苷酸缺失都不会消除 IRES 活性。此外，从全长 SVA cDNA 克隆内的 13-nt 序列中逐个删除一个核苷酸。结果表明，从 1 到 5 个核苷酸缺失的 cDNA 克隆中可以拯救出核苷酸缺失的 SVA，而在体外连续传代 9 次时，只有 1 到 2 个核苷酸缺失的病毒在遗传上是稳定的。此外，只有 1 个核苷酸缺失的 SVA 显示出与野生型病毒相似的生长动力学，表明假结-AUG 距离对 SVA 复制至关重要。
