Department of Molecular Biology, Lewis Thomas Laboratory, Princeton University, Princeton, New Jersey, USA.
Division of Gastroenterology & Hepatology, Department of Medicine, Weill Medical College of Cornell University, New York, New York, USA.
mBio. 2018 May 8;9(3):e00769-18. doi: 10.1128/mBio.00769-18.
Approximately 20 million hepatitis E virus (HEV) infections occur annually in both developing and industrialized countries. Most infections are self-limiting, but they can lead to chronic infections and cirrhosis in immunocompromised patients, and death in pregnant women. The mechanisms of HEV replication remain incompletely understood due to scarcity of adequate experimental platforms. HEV undergoes asymmetric genome replication, but it produces an additional subgenomic (SG) RNA encoding the viral capsid and a viroporin in partially overlapping open reading frames. Using a novel transcomplementation system, we mapped the intragenomic subgenomic promoter regulating SG RNA synthesis. This -acting element is highly conserved across all eight HEV genotypes, and when the element is mutated, it abrogates particle assembly and release. Our work defines previously unappreciated viral regulatory elements and provides the first in-depth view of the intracellular genome dynamics of this emerging human pathogen. HEV is an emerging pathogen causing severe liver disease. The genetic information of HEV is encoded in RNA. The genomic RNA is initially copied into a complementary, antigenomic RNA that is a template for synthesis of more genomic RNA and for so-called subgenomic RNA. In this study, we identified the precise region within the HEV genome at which the synthesis of the subgenomic RNA is initiated. The nucleotides within this region are conserved across genetically distinct variants of HEV, highlighting the general importance of this segment for the virus. To identify this regulatory element, we developed a new experimental system that is a powerful tool with broad utility to mechanistically dissect many other poorly understood functional elements of HEV.
每年在发展中国家和发达国家，大约有 2000 万例戊型肝炎病毒（HEV）感染。大多数感染是自限性的，但它们可导致免疫功能低下的患者发生慢性感染和肝硬化，并可导致孕妇死亡。由于缺乏足够的实验平台，HEV 的复制机制仍不完全清楚。HEV 经历不对称的基因组复制，但它在部分重叠的开放阅读框中产生额外的亚基因组（SG）RNA 编码病毒衣壳和病毒孔蛋白。使用新型的转互补系统，我们绘制了调节 SG RNA 合成的基因组内亚基因组启动子。这个 -作用元件在所有 8 种 HEV 基因型中高度保守，当元件发生突变时，它会破坏颗粒组装和释放。我们的工作定义了以前未被认识的病毒调节元件，并提供了对这种新兴人类病原体细胞内基因组动态的首次深入观察。HEV 是一种引起严重肝脏疾病的新兴病原体。HEV 的遗传信息编码在 RNA 中。基因组 RNA 最初被复制成互补的反基因组 RNA，反基因组 RNA 是合成更多基因组 RNA 和所谓的亚基因组 RNA 的模板。在这项研究中，我们确定了 HEV 基因组中最初开始合成亚基因组 RNA 的精确区域。该区域内的核苷酸在遗传上不同的 HEV 变体中是保守的，突出了该片段对病毒的普遍重要性。为了鉴定这个调节元件，我们开发了一种新的实验系统，这是一个具有广泛用途的强大工具，可以从机制上剖析许多其他尚未充分了解的 HEV 功能元件。
