Hepatitis delta virus RNA editing

描述（申请人提供）：丁型肝炎病毒（HDV）是一种独特的人类病原体，是病毒学和RNA生物学的重要模型系统。本研究的目的是了解宿主腺苷脱氨酶ADAR1调控HDV RNA特异性编辑的机制。了解这些机制将为我们进一步了解HDV的复制和发病机制以及通过腺苷脱胺进行RNA编辑提供基础，腺苷脱胺是细胞和病毒基因转录后重要的调控机制。HDV通过编辑来延长病毒蛋白的阅读框，形成一种名为HDAg-L的形式，这种形式既能形成病毒颗粒供分泌，又能抑制病毒RNA复制。因此，病毒琥珀/W位点的RNA编辑在HDV复制周期中起着核心作用。编辑所需的RNA序列和结构，以及添加到HDAg-L中对其包装和抑制功能至关重要的序列，是三种HDV基因型的显著特征。我们建议对三种HDV基因型中的编辑和HDAg-L功能进行比较分析，将为HDV控制编辑的机制以及编辑水平与HDAg-L在HDV复制周期中的作用之间的关系提供有价值的见解。由于编辑在HDV生命周期中的核心作用，该分析也可能为HDV基因型之间致病变异的机制基础提供关键见解。具体目的是：1)确定三种HDV基因型中不同RNA结构元件对琥珀/W位点HDV RNA编辑的贡献；2)确定RNA结构动力学在HDV基因III型RNA编辑和复制中的作用和机制；3)确定HDV基因型I和III中RNA编辑调控的不同机制；4)比较和对比病毒蛋白HDAg-L在ⅰ型和ⅲ型HDV包装和复制中的功能特性。

DESCRIPTION (provided by applicant): Hepatitis delta virus (HDV) is a unique human pathogen that serves as an important model system for both virology and RNA biology. The goal in this proposal is to understand the mechanisms by which HDV RNA and protein structures regulate the specific editing of HDV RNA by a host adenosine deaminase, ADAR1. Understanding these mechanisms will provide a basis for advancing our understanding of HDV replication and pathogenesis, as well as RNA editing via adenosine deamination, which is increasingly recognized as an important post-transcriptional regulatory mechanism for both cellular and viral genes. HDV uses editing to extend the reading frame of the viral protein to make a form, HDAg-L, which both forms virus particles for secretion and inhibits viral RNA replication. Thus, RNA editing at the viral amber/W site plays a central role in the HDV replication cycle. The RNA sequences and structures required for editing, and the sequences added to HDAg-L that are essential for its packaging and inhibitory functions, are distinguishing features of the three HDV genotypes. We propose that comparative analysis of editing and HDAg-L function among the three HDV genotypes will provide valuable insight into the mechanisms by which HDV controls editing, and the relationship between editing levels and the role of HDAg-L in the HDV replication cycle. Because of the central role if editing in the HDV life cycle, this analysis is also likely to provide critical insights into the mechanistic basis for pathogenic variations among the HDV genotypes. The specific aims are: 1) to determine the contributions of different RNA structural elements to editing HDV RNA at the amber/W site in the three HDV genotypes; 2) determine the role and mechanism of RNA structural dynamics in HDV genotype III RNA editing and replication; 3) to determine the different mechanisms by which RNA editing is regulated in HDV genotypes I and III; and 4) to compare and contrast the functional properties of the viral protein HDAg-L in packaging and replication of HDV genotypes I and III.