Discovery of a novel bandavirus using metagenomic sequencing in a retrospective analysis of an unresolved 2020 mortality event involving wild black vultures in the northeastern United States.

Investigations of wildlife diseases and mortality events can sometimes lead to inconclusive results because of limitations in testing combined with an ever-increasing number of emerging viruses. The use of tools such as unbiased metagenomic next-generation sequencing (mNGS) can facilitate the identification of causative agents when conventional investigation methods fail. We performed a retrospective mNGS analysis on RNA isolated from postmortem samples collected during a mortality event in free-ranging, wild black vultures (<i>Coragyps atratus</i>) that occurred in eastern Pennsylvania and western New Jersey in 2020. We describe the discovery and identification of a novel species of bandavirus (family <i>Phenuiviridae</i>) in case specimens from this die-off, as well as some of the associated pathology findings. The <i>Bandavirus</i> genus comprises tickborne viral species that have been reported across 5 continents. These viruses have been implicated in outbreaks in a variety of mammalian hosts, including humans, and in avian species, making them important potential sources of zoonotic spillover events. Genomic and phylogenetic analyses of the bandavirus that we detected indicate that its closest relative is Hunter Island virus, a bandavirus previously implicated in albatross mortality events off the coast of Tasmania, Australia. Follow-up PCR testing of samples from 16 additional vultures from the same cohort indicate that this new bandavirus was the likely cause of death.