Characterization of a novel Tombusviridae species isolated from Paris polyphylla var. yunnanensis.

A novel virus, Paris virus 2 (ParV2), was isolated from diseased Paris polyphylla var. yunnanensis, and its complete genome sequence was determined and analyzed. ParV2 is a positive-sense single-stranded RNA (+ssRNA) virus with a genome size of 4,118 nucleotides. The ParV2 genome contains six putative open reading frames (ORFs) that encode proteins with predicted molecular weights of 40.14, 100.26, 7.31, 7.85, 26.09, and 8.77 kDa. The first ORF (ORF1) of ParV2 encodes a putative protein of 40.14 kDa (P40, nt: 20-1,096), whiles the second ORF (ORF2, 888 aa) containing the GDD motif encodes the highly conserved RNA-dependent RNA polymerase protein (RdRP, nt:20-2,683, P100, 100.26 kDa) of viruses in the family Tombusviridae. Multiple sequence alignments analysis showed that the complete genome sequence of ParV2 shares 31.7-55.5% nucleotide sequence identities with viruses in the family Tombusviridae. Ginger chlorotic fleck-associated tombusvirus (GCFaV-1, Accession No. QKE30557) had the highest sequence identity (55.5%) with ParV2. GCFaV-1 also shares 59.2% RdRP and 34.9% CP amino acid sequence identities with ParV2. Sequence comparisons and phylogenetic analysis of RdRP suggested that ParV2 is a novel member of the family Tombusviridae, and its closest known relative is GCFaV-1.