State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China.
Analysis Center of Agrobiology and Environmental Sciences, Zhejiang University, Hangzhou 310058, China.
Viruses. 2022 May 27;14(6):1159. doi: 10.3390/v14061159.
Nodaviruses are small bipartite RNA viruses and are considered animal viruses. Here, we identified two novel noda-like viruses (referred to as rice-associated noda-like virus 1 (RNLV1) and rice-associated noda-like virus 2 (RNLV2)) in field-collected rice plants showing a dwarfing phenotype through RNA-seq. RNLV1 genome consists of 3335 nt RNA1 and 1769 nt RNA2, and RNLV2 genome consists of 3279 nt RNA1 and 1525 nt RNA2. Three conserved ORFs were identified in each genome of the two novel viruses, encoding an RNA-dependent RNA polymerase, an RNA silencing suppressor, and a capsid protein, respectively. The results of sequence alignment, protein domain prediction, and evolutionary analysis indicate that these two novel viruses are clearly different from the known nodaviruses, especially the CPs. We have also determined that the B2 protein encoded by the two new noda-like viruses can suppress RNA silencing in plants. Two reverse genetic systems were constructed and used to show that RNLV1 RNA1 can replicate in plant cells and RNLV1 can replicate in insect Sf9 cells. We have also found two unusual peptidase family A21 domains in the RNLV1 CP, and RNLV1 CP can self-cleave in acidic environments. These findings provide new knowledge of novel nodaviruses.
诺达病毒是一种小型二分体 RNA 病毒，被认为是动物病毒。在这里，我们通过 RNA-seq 从表现出矮化表型的田间采集的水稻植物中鉴定出两种新型的拟诺达病毒（称为水稻相关拟诺达病毒 1（RNLV1）和水稻相关拟诺达病毒 2（RNLV2））。RNLV1 基因组由 3335nt RNA1 和 1769nt RNA2 组成，RNLV2 基因组由 3279nt RNA1 和 1525nt RNA2 组成。两种新型病毒的每个基因组中都鉴定出三个保守的 ORF，分别编码 RNA 依赖性 RNA 聚合酶、RNA 沉默抑制子和衣壳蛋白。序列比对、蛋白结构域预测和进化分析的结果表明，这两种新型病毒与已知的诺达病毒明显不同，尤其是 CP。我们还确定，两种新的拟诺达病毒编码的 B2 蛋白可以在植物中抑制 RNA 沉默。构建了两种反向遗传学系统，并用于表明 RNLV1 RNA1 可以在植物细胞中复制，RNLV1 可以在昆虫 Sf9 细胞中复制。我们还在 RNLV1 CP 中发现了两个不寻常的 A21 肽酶家族结构域，并且 RNLV1 CP 可以在酸性环境中自我切割。这些发现为新型诺达病毒提供了新的知识。
