Phytopathology. 1998 Apr;88(4):351-8. doi: 10.1094/PHYTO.1998.88.4.351.
ABSTRACT Double-stranded genomic RNAs (dsRNAs) extracted from Chenopodium quinoa infected with watermelon silver mottle virus (WSMV) were similar to those of tomato spotted wilt virus (TSWV, serogroup I) and impatiens necrotic spot virus (INSV, serogroup III), except that the S dsRNA of WSMV is 0.75 and 0.6 kbp longer than those of TSWV and INSV, respectively. The complete nucleotide sequence of the genomic M RNA of WSMV was determined from cDNA clones generated from separated M dsRNA. The M RNA is 4,880 nucleotides in length with two open reading frames (ORFs) in an ambisense organization. The M RNA-encoded nonstructural (NSm) ORF located on the viral strand encodes a protein of 312 amino acids (35 kDa), and the G1/G2 ORF located on the viral complementary strand encodes a protein of 1,121 amino acids (127.6 kDa). The RNA probe corresponding to the NSm or G1/G2 ORF of WSMV failed to hybridize with the M dsRNAs of TSWV and INSV. Comparison of M and S RNAs of WSMV, TSWV, INSV, and peanut bud necrosis virus (PBNV, serogroup IV) revealed a consensus sequence of eight nucleotides of 5'-AGAGCAAU...-3' at their 5' ends and 5'-...AUUGCUCU-3' at their 3' ends. The low overall nucleotide identities (56.4 to 56.9%) of the M RNA and the low amino acid identities of the NSm and G1/G2 proteins (30.5 to 40.9%) with those of TSWV and INSV indicate that WSMV belongs to the Tospovirus genus but is phylogenetically distinct from viruses in serogroups I and III. The M RNA of WSMV shares a nucleotide identity of 79.6% with that of PBNV, and the two viruses share 83.4 and 88.7% amino acid identities for their NSm and G1/G2 proteins, respectively. It is concluded that they are two related but distinct species of serogroup IV. In addition to the viral or viral complementary full-length M RNA, two putative RNA messages for the NSm gene and the G1/G2 gene, 1.0 and 3.4 kb, respectively, were detected from the total RNA extracted from WSMV-infected tissue of Nicotiana benthamiana. The 1.0- and 3.4-kb RNAs were also detected in the viral RNAs extracted from purified nucleocapsids, suggesting that the putative messages of the M RNA of WSMV can also be encapsidated by the nucleocapsid protein.
摘要 从感染西瓜银斑驳病毒（WSMV）的藜感染植株中提取的双链基因组 RNA（dsRNA）与番茄斑萎病毒（TSWV，血清Ⅰ组）和凤仙花坏死斑点病毒（INSV，血清Ⅲ组）的 dsRNA 相似，只是 WSMV 的 S 基因组 RNA 比 TSWV 和 INSV 的 S 基因组 RNA 分别长 0.75 和 0.6kb。WSMV 基因组 M RNA 的全长核苷酸序列是从分离的 M dsRNA 生成的 cDNA 克隆中确定的。M RNA 长 4880 个核苷酸，具有在反义方向上的两个开放阅读框（ORF）。M RNA 编码的非结构（NSm）ORF 位于病毒链上，编码 312 个氨基酸（35kDa）的蛋白，而位于病毒互补链上的 G1/G2 ORF 编码 1121 个氨基酸（127.6kDa）的蛋白。与 WSMV 的 NSm 或 G1/G2 ORF 相对应的 RNA 探针未能与 TSWV 和 INSV 的 M dsRNA 杂交。WSMV、TSWV、INSV 和花生芽坏死病毒（PBNV，血清Ⅳ组）的 M 和 S RNA 的比较显示，它们 5' 端有一个 8 个核苷酸的保守序列 5'-AGAGCAAU...-3'，3' 端有一个 5'-...AUUGCUCU-3'。M RNA 的整体核苷酸同一性（56.4%至 56.9%）和 NSm 和 G1/G2 蛋白的低氨基酸同一性（30.5%至 40.9%）与 TSWV 和 INSV 相比表明，WSMV 属于 Tospovirus 属，但在系统发育上与血清Ⅰ组和Ⅲ组的病毒不同。WSMV 的 M RNA 与 PBNV 的 M RNA 的核苷酸同一性为 79.6%，两者的 NSm 和 G1/G2 蛋白的氨基酸同一性分别为 83.4%和 88.7%。由此得出结论，它们是血清Ⅳ组的两个相关但不同的种。除了病毒或病毒互补全长 M RNA 外，从感染 Nicotiana benthamiana 的 WSMV 组织中提取的总 RNA 中还检测到两个假定的 NSm 基因和 G1/G2 基因的 RNA 消息，分别为 1.0 和 3.4kb。从纯化的核衣壳蛋白中提取的病毒 RNA 中也检测到了 1.0 和 3.4kb RNA，这表明 WSMV 的 M RNA 的假定消息也可以被核衣壳蛋白包裹。
