Identification and molecular characterization of a novel kudzu-infecting virus of the family Betaflexiviridae

A new virus, tentatively named “kudzu virus D” (KuVD) was discovered in kudzu ( Pueraria montana var. lobata ) in South Korea. Its complete genome comprises 7,922 nucleotides, excluding the poly(A) tail, and contains five open reading frames (ORFs) encoding, from 5′ to 3′, a replicase (ORF1), three triple gene block proteins TGB1–3 (ORF2–ORF4), and a coat protein (ORF5). This genome organization is typical of members of the subfamily Quinvirinae of the family Betaflexiviridae . Pairwise alignment analysis revealed that the nucleotide sequences of the replicase and coat protein of KuVD were 12.13-54.46% and 24.03-50.67% identical, respectively, to those of other members of the family Betaflexiviridae . These values are far below the current species ICTV demarcation threshold. Consequently, KuVD should be considered a member of a new species in the subfamily Quinvirinae .