Tahiri-Alaoui Abdessamad, Smith Lorraine P, Baigent Suzan, Kgosana Lydia, Petherbridge Lawrence J, Lambeth Luke S, James William, Nair Venugopal
Division of Microbiology, Institute for Animal Health, Compton, Berkshire, United Kingdom.
J Virol. 2009 Jun;83(11):5846-53. doi: 10.1128/JVI.02602-08. Epub 2009 Mar 18.
In this study, we have identified an internal ribosome entry site (IRES) from the highly infectious herpesvirus Marek's disease virus (MDV). The IRES was mapped to the intercistronic region (ICR) of a bicistronic mRNA that we cloned from the MDV-transformed CD4(+) T-cell line MSB-1. The transcript is a member of a family of mRNAs expressed as immediate-early genes with two open reading frames (ORF). The first ORF encodes a 14-kDa polypeptide with two N-terminal splice variants, whereas the second ORF is contained entirely within a single exon and encodes a 12-kDa protein also known as RLORF9. We have shown that the ICR that separates the two ORFs functions as an IRES that controls the translation of RLORF9 when cap-dependent translation is inhibited. Deletion analysis revealed that there are two potential IRES elements within the ICR. Reverse genetic experiments with the oncogenic strain of MDV type 1 indicated that deletion of IRES-controlled RLORF9 does not significantly affect viral replication or MDV-induced mortality.
在本研究中，我们从具有高度传染性的疱疹病毒马立克氏病病毒（MDV）中鉴定出一个内部核糖体进入位点（IRES）。该IRES被定位到我们从MDV转化的CD4(+) T细胞系MSB-1中克隆的双顺反子mRNA的顺反子间区域（ICR）。该转录本是作为具有两个开放阅读框（ORF）的立即早期基因表达的mRNA家族的成员。第一个ORF编码一个具有两个N端剪接变体的14 kDa多肽，而第二个ORF完全包含在单个外显子内，编码一个也被称为RLORF9的12 kDa蛋白。我们已经表明，当帽依赖性翻译受到抑制时，分隔两个ORF的ICR作为一个控制RLORF9翻译的IRES发挥作用。缺失分析表明，ICR内有两个潜在的IRES元件。用1型MDV的致癌株进行的反向遗传实验表明，IRES控制的RLORF9的缺失不会显著影响病毒复制或MDV诱导的死亡率。
