Discovery of a Novel Member of the Carlavirus Genus from Soybean (Glycine max L. Merr.)

A novel member of the Carlavirus genus, provisionally named soybean carlavirus 1 (SCV1), was discovered by RNA-seq analysis of randomly collected soybean leaves in Illinois, USA. The SCV1 genome contains six open reading frames that encode a viral replicase, triple gene block proteins, a coat protein (CP) and a nucleic acid binding protein. The proteins showed highest amino acid sequence identities with the corresponding proteins of red clover carlavirus A (RCCVA). The predicted amino acid sequence of the SCV1 replicase was only 60.6% identical with the replicase of RCCVA, which is below the demarcation criteria for a new species in the family Betaflexiviridae. The predicted replicase and CP amino acid sequences of four SCV1 isolates grouped phylogenetically with those of members of the Carlavirus genus in the family Betaflexiviridae. The features of the encoded proteins, low nucleotide and amino acid sequence identities of the replicase with the closest member, and the phylogenetic grouping suggest SCV1 is a new member of the Carlavirus genus.