Whole genome sequencing of orthoreovirus isolated from Sea otters in Alaska
Increased mortality events of Sea otters (E. lutris kenyoni) near Katchemak Bay, Alaska, led to a surveillance study to determine the cause of increased deaths. From this study two separate virus isolates, EL1562 and EL1411, were obtained and sent for whole genome sequencing. EL1562 was also cultured to aid in characterisation and genome sequencing. Cytopathic effects were observed in both BWK and Vero.DogSLAMtag cells inoculated with EL1562 along with no signs of syncytia. Transmission electron microscopy of infected cells showed cytoplasmic clusters of icosahedral capsid viral particles consistent with the family Reoviridae. The whole genome of two different viruses belonging to the genus Orthoreovirus was obtained through next-generation sequencing. EL1411 was determined to belong to the clade of mammalian orthoreoviruses, while EL1562 shows higher identity to phocid orthoreovirus 1 previously isolated from Harbor seals in Washington State in 2008. Phylogenetic analysis of EL1562 is consistent with it belonging to a novel sister species of orthoreovirus to that of mammalian orthoreovirus. Based on the results this study represents the first instance of an orthoreovirus that was cultured and whole genome sequenced from Sea otters, and only the second report of mammalian orthoreovirus in marine mammals.