Complete genome sequence and molecular characterization of a novel potyvirus (sweet potato virus H) infecting sweet potato.

Sweet potato (Ipomoea batatas [L.] Lam.), an important food crop, is extensively cultivated in more than 100 countries and regions worldwide, particularly in developing countries. In this study, a novel RNA virus, tentatively named "sweet potato virus H" (SPVH), with the proposed species name "Potyvirus hebatatae", was identified in Hainan, China. Its complete genomic sequence was obtained through small-RNA sequencing (sRNA-seq) technology and RT-PCR. The viral genome is 10,901 nt in length (excluding the 3'-terminal poly(A) tail) and encodes a putative polyprotein of 3,498 amino acids. The genomic structure of SPVH is similar to that of sweet potato feathery mottle virus (SPFMV). The cleavage sites and conserved motifs of the SVPH polyprotein were analyzed, and the nucleotide and amino acid sequences were compared with those of other SPFMV subgroup viruses. Pairwise comparisons revealed that the complete genome of SPVH shared 64.2-68.4% nucleotide sequence identity and the polyprotein shared 66.7-71.8% amino acid sequence identity with other SPFMV subgroup viruses (NC001841, NC014742, NC017970, NC018093, and MH388502). Phylogenetic analysis showed that SPVH was grouped into a separate branch closer to SPFMV and sweet potato virus C (SPVC) within the potyvirus subgroup. These results suggest that SPVH is a new member of the genus Potyvirus.