Abstract：
Mammalian arenavirus (mammarenavirus) mRNAs are characterized by 5\'-capped and 3\'-nonpolyadenylated untranslated regions (UTRs). We previously reported that the nonpolyadenylated 3\'-UTR of viral mRNA (vmRNA), which is derived from the noncoding intergenic region (IGR), regulates viral protein levels at the posttranscriptional level. This finding provided the basis for the development of novel live-attenuated vaccines (LAVs) against human pathogenic mammarenaviruses. Detailed information about the roles of specific vmRNA 3\'-UTR sequences in controlling translation efficiency will help in understanding the mechanism underlying attenuation by IGR manipulations. Here, we characterize the roles of cis-acting mRNA regulatory sequences of a prototypic mammarenavirus, lymphocytic choriomeningitis virus (LCMV), in modulating translational efficiency. Using in vitro transcribed RNA mimics encoding a reporter gene, we demonstrate that the 3\'-UTR of nucleoprotein (NP) mRNA without a poly(A) tail promotes translation in a poly(A)-binding protein-independent manner. Comparison with the 3\'-UTR of glycoprotein precursor mRNA, which is translated less efficiently, revealed that a 10-nucleotide sequence proximal to the NP open reading frame is essential for promoting translation. Modification of this 10-nucleotide sequence also impacted reporter gene expression in recombinant LCMV. Our findings will enable rational design of the 10-nucleotide sequence to further improve our mammarenavirus LAV candidates and to develop a novel LCMV vector capable of controlling foreign gene expression.
摘要：
哺乳动物沙粒病毒(哺乳动物病毒)mRNA的特征在于5'-加帽和3'-非聚腺苷酸化非翻译区(UTR)。我们以前报道了病毒mRNA(vmRNA)的非多聚腺苷酸化3'-UTR，它来自非编码基因间区域(IGR)，在转录后水平调节病毒蛋白水平。这一发现为开发抗人致病性哺乳动物病毒的新型减毒活疫苗（LAV）提供了基础。有关特定vmRNA3'-UTR序列在控制翻译效率中的作用的详细信息将有助于理解IGR操作减弱的潜在机制。这里,我们描述了原型哺乳动物病毒的顺式作用mRNA调节序列的作用，淋巴细胞脉络膜脑膜炎病毒（LCMV），在调节翻译效率方面。使用体外转录的RNA模拟编码报告基因，我们证明，没有poly（A）尾的核蛋白（NP）mRNA的3'-UTR以不依赖poly（A）结合蛋白的方式促进翻译。与糖蛋白前体mRNA的3'-UTR比较，翻译效率较低，揭示了邻近NP开放阅读框的10个核苷酸的序列对于促进翻译至关重要。该10个核苷酸序列的修饰也影响了重组LCMV中的报告基因表达。我们的发现将使10个核苷酸序列的合理设计能够进一步改善我们的哺乳动物病毒LAV候选物，并开发能够控制外源基因表达的新型LCMV载体。
