Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, USA.
Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, USA
J Virol. 2018 Aug 16;92(17). doi: 10.1128/JVI.00416-18. Print 2018 Sep 1.
RNA interference (RNAi) is a widespread antiviral mechanism triggered by virus-produced double-stranded RNAs (dsRNAs). In , antiviral RNAi involves a RIG-I-like RNA helicase, termed DRH-1 (dicer related RNA helicase 1), that is not required for classical RNAi triggered by artificial dsRNA. Currently, whether antiviral RNAi in involves novel factors that are dispensable for classical RNAi remains an open question. To address this question, we designed and carried out a genetic screen that aims to identify novel genes involved in worm antiviral RNAi. By introducing extra copies of known antiviral RNAi genes into the reporter worms, we managed to reject alleles derived from 4 known antiviral RNAi genes, including the DRH-1 coding gene, during the screen. Our genetic screen altogether identified 25 alleles, which were assigned to 11 candidate genes and 2 known antiviral RNAi genes through genetic complementation tests. Using a mapping-by-sequencing strategy, we identified one of the candidate genes as , a gene that helps maintain genome integrity through an endogenous gene-silencing pathway but was not known to be required for antiviral RNAi. More importantly, we found that two of the candidate genes are required for antiviral RNAi targeting Orsay virus, a natural viral pathogen of , but dispensable for classical RNAi. Since is so far the only antiviral RNAi gene not required for classical RNAi, we believe that our genetic screen led to identification of novel worm genes that may target virus-specific features to function in RNAi. In nematode worms, detects virus-produced double-stranded RNA (dsRNA), thereby specifically contributing to antiviral RNA silencing. To identify -like genes with dedicated function in antiviral RNAi, we recently carried out a genetic screen that was designed to automatically reject all alleles derived from 4 known antiviral silencing genes, including Of the 11 candidate genes identified, we found two of them to be required for antiviral silencing targeting a natural viral pathogen of but not for classical RNA silencing triggered by artificial dsRNA. We believe that these two genes are novel components of worm antiviral RNAi, considering the fact that is the only known antiviral RNAi gene that is dispensable for classical RNAi. This genetic screen also identified , a gene that maintains genome integrity under unfavorable conditions, as a key regulator of worm antiviral silencing, demonstrating an interplay between antiviral immunity and genome integrity maintenance.
RNA 干扰 (RNAi) 是一种广泛存在的抗病毒机制，由病毒产生的双链 RNA (dsRNA) 触发。在 中，抗病毒 RNAi 涉及一种称为 DRH-1（dicer 相关 RNA 解旋酶 1）的 RIG-I 样 RNA 解旋酶，它不是经典 RNAi 触发所必需的。目前， 中抗病毒 RNAi 是否涉及对经典 RNAi 不重要的新因素仍然是一个悬而未决的问题。为了解决这个问题，我们设计并进行了一项遗传筛选，旨在鉴定参与蠕虫抗病毒 RNAi 的新基因。通过将已知抗病毒 RNAi 基因的额外拷贝引入报告蠕虫中，我们设法在筛选过程中拒绝了源自 4 个已知抗病毒 RNAi 基因的等位基因，包括 DRH-1 编码基因。我们的遗传筛选总共鉴定出 25 个等位基因，通过遗传互补测试将它们分配到 11 个候选基因和 2 个已知抗病毒 RNAi 基因中。使用映射测序策略，我们鉴定出候选基因之一是 ，该基因通过内源性基因沉默途径帮助维持基因组完整性，但不被认为是抗病毒 RNAi 所必需的。更重要的是，我们发现候选基因中的两个基因是针对 Orsay 病毒的抗病毒 RNAi 所必需的，Orsay 病毒是 的天然病毒病原体，但对经典 RNAi 是可有可无的。由于 迄今为止是唯一不被经典 RNAi 所需的抗病毒 RNAi 基因，我们相信我们的遗传筛选导致了对可能针对病毒特异性特征以发挥 RNAi 功能的新的蠕虫基因的鉴定。在线虫蠕虫中， 检测病毒产生的双链 RNA (dsRNA)，从而特异性地有助于抗病毒 RNA 沉默。为了鉴定具有抗病毒 RNAi 专用功能的类似基因，我们最近进行了一项遗传筛选，旨在自动拒绝所有源自 4 个已知抗病毒沉默基因的等位基因，包括 在鉴定的 11 个候选基因中，我们发现其中两个基因对抗病毒沉默靶向 的天然病毒病原体是必需的，但对抗病毒 RNA 沉默是不必要的，而后者是由人工 dsRNA 触发的。鉴于 是唯一已知的对经典 RNAi 可有可无的抗病毒 RNAi 基因，我们认为这两个基因是蠕虫抗病毒 RNAi 的新组成部分。该遗传筛选还鉴定出 ，在不利条件下维持基因组完整性的基因，作为蠕虫抗病毒沉默的关键调节剂，展示了抗病毒免疫与基因组完整性维持之间的相互作用。
