Complete genome and molecular characterization of a putative novel citrivirus from Rudbeckia sp.

We identified a tentative novel positive-strand RNA virus from Rudbeckia sp., namely, Rudbeckia citrivirus A (RuCVA). The complete genome sequence of the novel virus was 8821 nucleotides in length, excluding the poly(A) tail. It has three open reading frames (ORFs): a putative polyprotein, a movement protein, and a coat protein. Phylogenetic analysis showed that the virus was more closely related to Citrus leaf blotch virus isolates and unassigned citriviruses. The sequence identity of the virus with other citriviruses was lower than 56.9% at the complete nucleotide sequence level. For each ORF, the sequence identity was lower than 64.2% at the nucleotide level and 67.8% at the amino acid level. These results satisfied the species demarcation criteria for Betaflexiviridae. Therefore, we suggest that RuCVA is a novel member of the genus Citrivirus.