State Key Laboratory of Agricultural Microbiology, Hubei Key Laboratory of Plant Pathology, Huazhong Agricultural University, Wuhan 430070, Hubei Province, China.
Provincial Key Laboratory of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
Viruses. 2019 Aug 16;11(8):759. doi: 10.3390/v11080759.
Infection by diverse mycoviruses is a common phenomenon in Sclerotinia sclerotiorum. In this study, the full genome of a single-stranded RNA mycovirus, tentatively named Hubei sclerotinia RNA virus 1 (HuSRV1), was determined in the hypovirulent strain 277 of S. sclerotiorum. The HuSRV1 genome is 4492 nucleotides (nt) long and lacks a poly (A) tail at the 3'- terminus. Sequence analyses showed that the HuSRV1 genome contains four putative open reading frames (ORFs). ORF1a was presumed to encode a protein with a conserved protease domain and a transmembrane domain. This protein is 27% identical to the P2a protein encoded by the subterranean clover mottle virus. ORF1b encodes a protein containing a conserved RNA-dependent RNA polymerase (RdRp) domain, which may be translated into a fusion protein by a -1 ribosome frameshift. This protein is 45.9% identical to P2b encoded by the sowbane mosaic virus. ORF2 was found to encode a putative coat protein, which shares 23% identical to the coat protein encoded by the olive mild mosaic virus. ORF3 was presumed to encode a putative protein with an unknown function. Evolutionary relation analyses indicated that HuSRV1 is related to members within Sobemovirus, but forms a unique phylogenetic branch, suggesting that HuSRV1 represents a new member within Solemoviridae. HuSRV1 virions, approximately 30 nm in diameter, were purified from strain 277. The purified virions were successfully introduced into virulent strain Ep-1PNA367, resulting in a new hypovirulent strain, which confirmed that HuSRV1 confers hypovirulence on S. sclerotiorum.
在核盘菌（Sclerotinia sclerotiorum）中，多种真菌病毒的感染是一种常见现象。本研究在核盘菌弱毒菌株 277 中，确定了一种单链 RNA 真菌病毒的全基因组，暂定名为湖北核盘菌 RNA 病毒 1（HuSRV1）。HuSRV1 基因组长 4492 个核苷酸（nt），在 3' 末端没有聚（A）尾。序列分析表明，HuSRV1 基因组包含四个推定的开放阅读框（ORF）。ORF1a 被推测编码一种具有保守蛋白酶结构域和跨膜结构域的蛋白。该蛋白与地下三叶草斑驳病毒编码的 P2a 蛋白有 27%的同一性。ORF1b 编码一种含有保守 RNA 依赖的 RNA 聚合酶（RdRp）结构域的蛋白，该蛋白可能通过 -1 核糖体移码翻译为融合蛋白。该蛋白与 sowbane mosaic virus 编码的 P2b 有 45.9%的同一性。ORF2 被发现编码一种假定的外壳蛋白，与 olive mild mosaic virus 编码的外壳蛋白有 23%的同一性。ORF3 被推测编码一种具有未知功能的假定蛋白。进化关系分析表明，HuSRV1 与 Sobemovirus 成员有关，但形成了一个独特的进化分支，表明 HuSRV1 代表了 Solemoviridae 中的一个新成员。从菌株 277 中纯化出的 HuSRV1 病毒粒子直径约为 30nm。纯化的病毒粒子成功地引入到毒力菌株 Ep-1PNA367 中，产生了一个新的弱毒菌株，这证实了 HuSRV1 使核盘菌产生弱毒。
