A novel rubi-like virus in the Pacific electric ray (<i>Tetronarce californica</i>) reveals the complex evolutionary history of the<i>Matonaviridae</i>

<jats:title>Abstract</jats:title><jats:p><jats:italic>Rubella virus</jats:italic>(RuV) is the causative agent of rubella (“German measles”) and remains a global health concern. Until recently, RuV was the only known member of the genus<jats:italic>Rubivirus</jats:italic>and the only virus species classified within the<jats:italic>Matonaviridae</jats:italic>family of positive-sense RNA viruses. Other matonaviruses, including two new rubella-like viruses,<jats:italic>Rustrela virus</jats:italic>and<jats:italic>Ruhugu virus</jats:italic>, have been identified in several mammalian species, along with more divergent viruses in fish and reptiles. To screen for the presence of additional novel rubella-like viruses we mined published transcriptome data using genome sequences from<jats:italic>Rubella, Rustrela</jats:italic>, and<jats:italic>Ruhugu viruses</jats:italic>as baits. From this, we identified a novel rubella-like virus in a transcriptome of<jats:italic>Tetronarce californica</jats:italic>(Pacific electric ray) that is more closely related to mammalian<jats:italic>Rustrela virus</jats:italic>than to the divergent fish matonavirus and indicative of a complex pattern of cross-species virus transmission. Analysis of host reads confirmed that the sample analysed was indeed from a Pacific electric ray, and two other viruses identified in this animal, from the<jats:italic>Arenaviridae</jats:italic>and<jats:italic>Reoviridae</jats:italic>, grouped with other fish viruses. These findings indicate that the evolutionary history of the<jats:italic>Matonaviridae</jats:italic>is more complex than previously thought and highlights the vast number of viruses still to be discovered.</jats:p>