Complete genome sequence of an umbravirus from white snakeroot (Ageratina altissima)

Complete genome sequencing of a virus from a white snakeroot plant (Ageratina altissima (L.) King & H. Rob.) collected in the Great Smoky Mountains National Park, USA, revealed a quadricistronic organization resembling that of umbraviruses. ORFs 1 and 2 are putatively translated via a -1 ribosomal frameshift mechanism as a single polypeptide with a role in viral replication, whereas the 3'-proximal and extensively overlapping ORFs 3 and 4 code for proteins involved in long distance trafficing and cell-to-cell movement within the host. Sequence comparisons and phylogenetic analysis strongly suggested that this virus is a previously undescribed member of the genus Umbravirus (family Tombusviridae), for which the name "white snakeroot virus A" (WSVA) is proposed. In addition, we identified and initiated characterization of its possible helper virus, a putative new member of the genus Luteovirus.