RNA silencing is as an adaptive immune response in plants that limits accumulation or spread of invading viruses. Successful virus infection entails countering the RNA silencing for efficient replication and systemic spread in the host. The viruses encode proteins having the ability to suppress or block the host silencing mechanism, resulting in severe pathogenic symptoms and diseases. Tungro virus disease caused by a complex of two viruses provides an excellent system to understand these host and virus interactions during infection. It is known that Rice tungro bacilliform virus (RTBV) is the major determinant of the disease while Rice tungro spherical virus (RTSV) accentuates the symptoms. This study brings to focus the important role of RTBV ORF-IV in Tungro disease manifestation, by acting as both the victim and silencer of the RNA silencing pathway. The ORF-IV is a weak suppressor of the S-PTGS or pre-established stable silencing but its suppression activity is augmented in the presence of RTSV proteins. The RTBV and RTSV proteins interact to suppress localized silencing as well as spread of silencing, in the host plants.

中文翻译：

---

RTBV和RTSV蛋白的协同作用抑制宿主RNA沉默机制

RNA沉默是植物中的一种适应性免疫反应，可限制入侵病毒的积累或传播。成功的病毒感染需要抵抗RNA沉默，以在宿主中进行有效复制和系统扩散。病毒编码的蛋白质具有抑制或阻断宿主沉默机制的能力，从而导致严重的病原体症状和疾病。由两种病毒复合物引起的通哥罗病毒病提供了一个很好的系统，可以了解感染期间这些宿主和病毒之间的相互作用。众所周知，水稻通格氏杆菌病毒（RTBV）是该疾病的主要决定因素，而水稻通格氏球形病毒（RTSV）会加剧症状。这项研究将重点放在RTBV ORF-IV在Tungro疾病表现中的重要作用，通过同时充当RNA沉默途径的受害者和沉默者。ORF-IV是S-PTGS的弱抑制剂或预先建立的稳定沉默，但在RTSV蛋白存在下其抑制活性增强。RTBV和RTSV蛋白相互作用以抑制宿主植物中的局部沉默以及沉默的传播。