Identification and complete genome sequence of a novel secovirus infecting Broussonetia kaempferi in China

In this study, a novel secovirid, tentatively named Broussonetia kaempferi secovirus (BkSV), was identified from a Broussonetia kaempferi transcriptome dataset. Its bipartite positive-sense RNA genome comprises two segments (6,300 nt and 3,564 nt), each encoding a single large polyprotein. The RNA1 polyprotein contains six conserved domains associated with replication, and the RNA2 polyprotein is cleaved into movement and coat proteins. Amino acid identities of the conserved regions between the 3 C-like proteinase and the RNA-directed RNA polymerase encoded on RNA1 and those of coat protein encoded on RNA2 relative to known members of Comovirinae were below species demarcation criteria. Phylogenetic analysis confirmed that BkSV represents a new species in the genus Mersevirus, family Secoviridae.