Data_Sheet_1_Identification and characterization of two closely related virga-like viruses latently infecting rubber trees (Hevea brasiliensis).docx

A novel virga-like virus, provisionally named Rubber tree latent virus 2 (RTLV2), was identified from rubber tree (Hevea brasiliensis). It is a close relative of the previously reported Rubber tree latent virus 1 (RTLV1). The complete genomes of RTLV1 and RTLV2 were sequenced and comparatively analyzed in terms of genome organization, putative gene products and phylogenetic relationship. Both RTLV1 and RTLV2 have positive-sense single-stranded RNA genomes that encode seven open reading frames (ORFs), forming a similar genomic layout. In phylogenetic analyses based on replicase and coat protein amino acid sequences, RTLV1 and RTLV2 were clustered with unclassified virga-like viruses. They are distinct from currently recognized plant virus families. RTLV1 and RTLV2 can be distinguished from members of Virgaviridae by the presence of a putative coat protein duplex and a poly(A) tail at the 3′-terminus. The authenticity of RTLV1 and RTLV2 as infectious viruses was confirmed through field investigations and transmissibility assays. In conclusion, RTLV1 and RTLV2 represent a novel plant virus group that does not readily fit into current virus families.

本研究从巴西橡胶树（Hevea brasiliensis）中鉴定出一株新型类轻花叶病毒，暂命名为橡胶树潜伏病毒2型（Rubber tree latent virus 2, RTLV2）。该病毒与此前报道的橡胶树潜伏病毒1型（RTLV1）亲缘关系密切。研究人员对RTLV1与RTLV2的完整基因组进行了测序，并从基因组结构、推定基因产物及系统发育关系等方面开展了比较分析。RTLV1与RTLV2均为正链单链RNA病毒，其基因组编码7个开放阅读框（open reading frame, ORF），二者基因组排布具有高度相似性。基于复制酶与衣壳蛋白氨基酸序列的系统发育分析显示，RTLV1与RTLV2与未分类的类轻花叶病毒聚为一支，且与当前已确认的植物病毒科均存在显著差异。二者可通过基因组3'端存在推定的衣壳蛋白双链结构及poly(A)尾这一特征，与轻花叶病毒科（Virgaviridae）成员相区分。通过田间调查及传毒试验，证实了RTLV1与RTLV2作为侵染性病毒的真实性。综上，RTLV1与RTLV2构成了一个新型植物病毒类群，难以归入现有病毒科。