Expanding the diversity of Celavirus, the most divergent genus in the family Potyviridae.

Abstract

Celavirus is a genus within the family Potyviridae, currently comprising a single recognized species, Celavirus apii, represented by celery latent virus (CeLV), and one additional potential member, Striga-associated poty-like virus 2 (SaPlV2). The Celavirus genome is highly divergent from those of other potyvirids, and its polyprotein architecture remains incompletely resolved. In this study, we conducted systematic mining of publicly available transcriptome datasets and identified eight novel celavirus-like viral genome contigs from five distinct sources, including Chrysanthemum × morifolium, Leucadendron linifolium, L. muirii, Dalzellia ubonensis, and mycorrhizal protocorms formed by Serapias vomeracea and Tulasnella calospora. Based on sequence comparisons and species demarcation criteria, these genome contigs likely represent four novel viral species. Phylogenetic analysis placed all novel viruses in a monophyletic clade with CeLV and SaPlV2, distinct from all other approved genera in the family Potyviridae. Conserved functional domains typical of potyvirid polyproteins, including CI, NIa-Pro, and NIb, were identified, whereas other canonical domains such as P1, HC-Pro, and CP were not detected, likely due to high sequence divergence. These findings expand the known diversity of Celavirus and offer new insights into its genome organization, host associations, and evolutionary position within the Potyviridae.