Institute of Plant Science and Resources, Okayama University, Okayama 710-0046, Japan.
Viruses. 2022 Aug 4;14(8):1722. doi: 10.3390/v14081722.
A novel dsRNA virus (Cryphonectria carpinicola fusagravirus 1, CcFGV1), isolated from a Japanese strain (JS13) of , was thoroughly characterized. The biological comparison of a set of isogenic CcFGV1-infected and -free (JS13VF) strains indicated asymptomatic infection by CcFGV1. The sequence analysis showed that the virus has a two open reading frame (ORF) genome of 9.6 kbp with the RNA-directed RNA polymerase domain encoded by ORF2. The N-terminal sequencing and peptide mass fingerprinting showed an N-terminally processed or degraded product (150 kDa) of the 5'-proximal ORF1-encoded protein (1462 amino acids) to make up the CcFGV1 spherical particles of ~40 nm in diameter. Interestingly, a portion of CcFGV1 dsRNA co-fractionated with a host protein of 70 kDa. The purified CcFGV1 particles were used to transfect protoplasts of JS13VF as well as the standard strain of an experimental model filamentous fungal host . CcFGV1 was confirmed to be associated with asymptomatic infection of both fungi. RNA silencing was shown to target the virus in , resulting in reduced CcFGV1 accumulation by comparing the CcFGV1 content between RNA silencing-competent and -deficient strains. These results indicate the transfectability of spherical particles of a fusagravirus associated with asymptomatic infection.
一种新型 dsRNA 病毒（Cryphonectria carpinicola fusagravirus 1，CcFGV1），从日本菌株（JS13）中分离出来，得到了全面的描述。对一组同源 CcFGV1 感染和非感染（JS13VF）菌株的生物学比较表明，CcFGV1 无症状感染。序列分析表明，该病毒具有 9.6 kbp 的双开放阅读框（ORF）基因组，其 RNA 指导的 RNA 聚合酶结构域由 ORF2 编码。N 端测序和肽质量指纹图谱显示，5'-近端 ORF1 编码蛋白（1462 个氨基酸）的 N 端加工或降解产物（150 kDa）构成了 CcFGV1 直径约 40 nm 的球形颗粒。有趣的是，部分 CcFGV1 dsRNA 与 70 kDa 的宿主蛋白共分离。纯化的 CcFGV1 颗粒用于转染 JS13VF 原生质体以及实验丝状真菌宿主的标准菌株。证实 CcFGV1 与两种真菌的无症状感染有关。RNA 沉默被证明靶向 中的病毒，通过比较 RNA 沉默能力和缺陷菌株之间的 CcFGV1 含量，导致 CcFGV1 积累减少。这些结果表明与无症状感染相关的 fusagravirus 球形颗粒的转染能力。
