Messenger RNA Capping and Methylation in Pneumoviruses

描述（由申请人提供）：副粘病毒是急性病毒性呼吸道感染的主要病原体。在副粘病毒中，人偏肺病毒（hMPV）、人呼吸道合胞病毒（RSV）和人副流感病毒3型（hPIV3）占急性病毒性呼吸道疾病的70%以上。尽管这些病毒造成了巨大的经济损失和情感负担，但目前还没有疫苗和抗病毒药物。副粘病毒的信使RNA （mRNA）的5'端包含一个独特的甲基化帽结构，该结构对病毒基因表达和随后的病毒复制至关重要。现有证据表明，副粘病毒mRNA帽结构的形成和甲基化与其宿主不同。这种差异可能被用作疫苗开发和抗病毒治疗的靶标。该项目将重点研究2001年首次发现的一种新发现的人类病原体hMPV。本项目的目的是了解hMPV中mRNA的capping和甲基化机制，并探索甲基转移酶作为开发新型hMPV疫苗的潜在靶点。我们的具体目标是：(1)明确hMPV中mRNA capping的机制；(2)明确mRNA帽甲基转移酶在hMPV中的作用机制；(3)生成甲基转移酶缺陷型hMPV，并确定甲基转移酶缺陷型病毒在细胞培养中是否减毒和遗传稳定；(4)确定甲基转移酶缺陷的hMPV在小鼠体内是否减毒和遗传稳定，以及是否可以用作候选活疫苗。这些研究不仅将大大提高我们对病毒mRNA盖顶和甲基化的理解，这是副粘病毒基因表达的重要步骤，而且还将填补我们对甲基转移酶在hMPV发病机制中的作用的理解的主要空白，特别是我们对甲基转移酶缺陷的hMPV是否可以用作活疫苗候选物的理解。从长远来看，我们的研究将有助于通过靶向病毒mRNA帽形成来合理设计新的疫苗和抗病毒药物。

DESCRIPTION (provided by applicant): Paramyxoviruses are the leading causative agents of acute viral respiratory tract infections. Among the paramyxoviruses, human metapneumovirus (hMPV), human respiratory syncytial virus (RSV), and human parainfluenza virus type 3 (hPIV3) account for more than 70% of acute viral respiratory diseases. Despite the enormous economic losses and emotional burdens these viruses cause, vaccines and anti- viral drugs are currently not available. The 5' end of the messenger RNA (mRNA) of paramyxoviruses contains a unique methylated cap structure that is essential for viral gene expression and, subsequently, viral replication. Available evidence suggests that formation and methylation of the paramyxovirus mRNA cap structure differs from that of their hosts. This difference could potentially be used as a target for vaccine development and anti-viral therapies. This project will be focused on hMPV, a newly discovered human pathogen, first identified in 2001. The objective of this project is to understand the mechanism of mRNA capping and methylation in hMPV and to explore methyltransferase as a potential target for the development of novel vaccines against hMPV. Our specific aims are: (1) to define the mechanism of mRNA capping in hMPV; (2) to define the mechanism of mRNA cap methyltransferase in hMPV; (3) to generate methyltransferase -defective hMPV and to determine whether methyltransferase -defective viruses are attenuated and genetically stable in cell culture; and (4) to determine whether methyltransferase -defective hMPV is attenuated and genetically stable in mice and if it can be used as a live vaccine candidate. The proposed studies will not only significantly advance our understanding of viral mRNA capping and methylation, an essential step in paramyxovirus gene expression, but will also fill in a major gap in our understanding of the role of methyltransferase in hMPV pathogenesis, specifically, our understanding of whether methyltransferase-defective hMPV can be used as a live vaccine candidates. In the long-term, our research will facilitate the rational design of new vaccines and anti-viral drugs by targeting viral mRNA cap formation. PUBLIC HEALTH RELEVANCE: Human metapneumovirus (hMPV) is one of the leading causative agents of acute viral respiratory tract infections. Currently, there is no vaccine or anti-viral drug. The objective of this project is to understand the mechanism of mRNA capping and methylation in hMPV, to explore the role of mRNA cap methylation in viral pathogenesis, and to develop methyltransferase-defective viruses as a live vaccine candidates for hMPV.