Plant and animal viruses overcome host antiviral silencing by encoding diverse viral suppressors of RNA silencing (VSRs). Prior to the identification and characterization of their silencing suppression activities mostly in transgene silencing assays, plant VSRs were known to enhance virus accumulation in the inoculated protoplasts, promote cell-to-cell virus movement in the inoculated leaves, facilitate the phloem-dependent long-distance virus spread, and/or intensify disease symptoms in systemically infected tissues. Here we discuss how the various silencing suppression activities of VSRs may facilitate these distinct steps during plant infection and why VSRs may not play a direct role in eliciting disease symptoms by general impairments of host endogenous small RNA pathways. We also highlight many of the key questions still to be addressed on the role of viral suppression of antiviral silencing in plant infection.

中文翻译：

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RNA沉默的病毒抑制因子在发病机理中的直接和间接作用。

植物和动物病毒通过编码RNA沉默（VSR）的多种病毒抑制剂来克服宿主抗病毒沉默。在鉴定和鉴定其沉默抑制活性（主要是在转基因沉默试验中）之前，已知植物VSR可增强接种原生质体中的病毒积累，促进接种叶片中细胞间的病毒移动，促进韧皮部依赖的长病毒在系统感染的组织中扩散和/或加剧疾病症状。在这里，我们讨论了VSR的各种沉默抑制活性如何在植物感染过程中促进这些不同的步骤，以及为什么VSR在宿主内源性小RNA途径的全面损伤中可能不直接引起疾病症状。