Xia Mingli, Yan Teng, Lu Rui
Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, 70803, USA.
Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, 70803, USA.
Virology. 2025 Jun 11;610:110597. doi: 10.1016/j.virol.2025.110597.
Cellular organisms are constantly challenged by potentially lethal viral infections and rely on diverse antiviral mechanisms for survival. In several systems, including plants and insects, parallel antiviral pathways provide redundancy, ensuring host protection even if one pathway is compromised by a virus. However, whether such alternative antiviral mechanisms exist in nematodes beyond RNA interference (RNAi) remains largely unexplored. To address this question and as proof of principle, we conducted a small-scale genetic screen to identify C. elegans genes involved in RNAi-independent antiviral defense (RiAD). The reporter system for this screen was a combination of a GFP-tagged flock house virus replicon, as the readout of efficient viral replication, and an RNAi-deficient triple mutant. The reporter C. elegans strain also carried a recessive E3 allele, which suppresses the replication of both flock house virus and Orsay virus. Because this reporter strain lacks a functional RNAi response, any restoration of viral replication in the screen is unlikely due to RNAi disruption, thereby enriching for mutants with defects in RiAD. Upon completing this biased genetic screen we identified ten recessive alleles which were assigned to eight candidate genes. Notably, five of these genes also contributed to RiAD against Orsay virus, indicating a role in broad-spectrum natural antiviral defense. Strikingly, removal of the E3 allele in one of the mutant backgrounds resulted in lethal Orsay virus infection, suggesting that RiAD plays a critical role in protecting C. elegans from fatal viral infection in the absence of RNAi under natural conditions.
细胞生物不断受到潜在致命病毒感染的挑战，并依靠多种抗病毒机制来生存。在包括植物和昆虫在内的几个系统中，并行的抗病毒途径提供了冗余性，即使一种途径被病毒破坏，也能确保宿主得到保护。然而，线虫中除RNA干扰（RNAi）之外是否存在此类替代抗病毒机制，在很大程度上仍未得到探索。为了解决这个问题并作为原理证明，我们进行了一项小规模的遗传筛选，以鉴定参与RNAi非依赖型抗病毒防御（RiAD）的秀丽隐杆线虫基因。该筛选的报告系统是一个绿色荧光蛋白（GFP）标记的禽成髓细胞瘤病毒复制子与一个RNAi缺陷型三重突变体的组合，前者作为有效病毒复制的读数。报告秀丽隐杆线虫菌株还携带一个隐性E3等位基因，它可抑制禽成髓细胞瘤病毒和奥赛病毒的复制。由于该报告菌株缺乏功能性RNAi反应，筛选中病毒复制的任何恢复都不太可能是由于RNAi破坏导致的，从而富集了RiAD有缺陷的突变体。在完成这个有偏向性的遗传筛选后，我们鉴定出了十个隐性等位基因，它们被分配到八个候选基因。值得注意的是，这些基因中的五个也对抵抗奥赛病毒的RiAD有贡献，表明其在广谱天然抗病毒防御中发挥作用。引人注目的是，在其中一个突变背景中去除E3等位基因会导致致命的奥赛病毒感染，这表明在自然条件下缺乏RNAi时，RiAD在保护秀丽隐杆线虫免受致命病毒感染方面起着关键作用。
