Dicer-2-and Piwi-Mediated RNA Interference in Rift Valley Fever Virus-Infected Mosquito Cells
Dicer-2-and Piwi-Mediated RNA Interference in Rift Valley Fever Virus-Infected Mosquito Cells
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DOI：
10.1128/jvi.02795-12
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发表时间：
2013-02-01
影响因子：
5.4
通讯作者：
Bouloy, M.
中科院分区：
文献类型：
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作者：
Leger, P.;Lara, E.;Bouloy, M.
裂谷热病毒（RVFV）是一种由蚊子传播的白蛉病毒（布尼亚病毒科）。它感染人类和反刍动物，在非洲、也门和沙特阿拉伯引起戏剧性的流行病和动物流行病。虽然最近的研究表明非结构蛋白NS作为脊椎动物毒力的主要组成部分的重要性，但对蚊子媒介的感染知之甚少。在这里，我们研究了RVFV感染三种不同的蚊子细胞系，Aag 2细胞从埃及伊蚊和U4.4和C6/36细胞从白纹伊蚊。与哺乳动物细胞相比，其中NS形成核丝，U4.4和Aag 2细胞下调NS表达，使得NS丝从未在U4.4细胞的核中形成，并且在Aag 2细胞感染后的早期消失。相反，在C6/36细胞中，NS核丝在整个感染过程中可见。通过深度测序对病毒衍生的小干扰RNA（viRNA）的分析表明，在C6/36细胞中viRNA的产生非常低，已知C6/36细胞是Dicer-2缺陷型的，但表达一些呈现Piwi特征的viRNA。相比之下，Aag 2和U4.4细胞产生大量主要匹配S片段并显示Dicer-2和Piwi特征的viRNA。尽管21-核苷酸（nt）Dicer-2 viRNA在早期感染期间是突出的，但24-至27-nt Piwi RNA（piRNA）的群体逐渐增加，并且在急性感染期间和持续期间变得占主导地位。在Aag 2和U4.4细胞中，Dicer-2和Piwi途径的联合作用触发了有效的抗病毒反应，除其他作用外，还允许抑制NS细丝形成并允许建立持久性。在C6/36细胞中，Piwi介导的RNA干扰（RNAi）似乎足以对重复感染病毒的继发感染产生抗病毒反应。这项研究为Dicer和Piwi在蚊子抗病毒防御中的作用以及蚊子抗病毒反应的发展提供了新的见解。
Rift Valley fever virus (RVFV) is a Phlebovirus (Bunyaviridae family) transmitted by mosquitoes. It infects humans and ruminants, causing dramatic epidemics and epizootics in Africa, Yemen, and Saudi Arabia. While recent studies demonstrated the importance of the nonstructural protein NSs as a major component of virulence in vertebrates, little is known about infection of mosquito vectors. Here we studied RVFV infection in three different mosquito cell lines, Aag2 cells from Aedes aegypti and U4.4 and C6/36 cells from Aedes albopictus. In contrast with mammalian cells, where NSs forms nuclear filaments, U4.4 and Aag2 cells downregulated NSs expression such that NSs filaments were never formed in nuclei of U4.4 cells and disappeared at an early time postinfection in the case of Aag2 cells. On the contrary, in C6/36 cells, NSs nuclear filaments were visible during the entire time course of infection. Analysis of virus-derived small interfering RNAs (viRNAs) by deep sequencing indicated that production of viRNAs was very low in C6/36 cells, which are known to be Dicer-2 deficient but expressed some viRNAs presenting a Piwi signature. In contrast, Aag2 and U4.4 cells produced large amounts of viRNAs predominantly matching the S segment and displaying Dicer-2 and Piwi signatures. Whereas 21-nucleotide (nt) Dicer-2 viRNAs were prominent during early infection, the population of 24- to 27-nt Piwi RNAs (piRNAs) increased progressively and became predominant later during the acute infection and during persistence. In Aag2 and U4.4 cells, the combined actions of the Dicer-2 and Piwi pathways triggered an efficient antiviral response permitting, among other actions, suppression of NSs filament formation and allowing establishment of persistence. In C6/36 cells, Piwi-mediated RNA interference (RNAi) appeared to be sufficient to mount an antiviral response against a secondary infection with a superinfecting virus. This study provides new insights into the role of Dicer and Piwi in mosquito antiviral defense and the development of the antiviral response in mosquitoes.