Complete nucleotide sequence of a new strain of Tobacco necrosis virus A infecting soybean in China and infectivity of its full-length cDNA clone
2008
Xi, Dehui | Li, Jiang | Han, Chenggui | Li, Dawei | Yu, Jialin | Zhou, Xueping
The complete nucleotide sequence of a virus isolated from soybean (Glycine max (L.) Merr.) in China, previously identified as a new strain of Tobacco necrosis virus A (TNV-A) based on its biological, serological properties, and coat protein (CP) sequence and named as TNV-AC, was determined and compared with that of TNV-A and other closely related Necroviruses and Carmoviruses. The viral RNA genome consists of 3,682 nucleotides and contains five open reading frames (ORFs). TNV-AC showed 86.4% overall nucleotide sequence identity to TNV-A. The CP and putative RNA-dependent RNA polymerase (RdRp) showed 88.8 and 95.9% amino acid identity, respectively, to that of TNV-A. The greatest difference between TNV-AC and TNV-A was in the 3′ terminal region: the p7K ORF region present in TNV-A was absent in TNV-AC. Phylogenetic analysis of RdRp, CP, and small ORF regions of Necroviruses confirmed TNV-AC as a new strain of TNV-A. A full-length cDNA clone of TNV-AC was constructed and used as template for run-off transcription based on the obtained sequence. The results indicate that the in vitro-synthesized viral RNA faithfully represented the biological activity of wild-type TNV-AC.
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