Fatal Encephalitis Caused by Cristoli Virus, an Emerging Orthobunyavirus, France

We report the discovery of a new orthobunyavirus, Cristoli virus, by means of shotgun metagenomics. The virus was identified in an immunodepressed patient with fatal encephalitis. Full-length genome sequencing revealed high-level expression of a virulence factor, possibly explaining the severity of the infection. The patient's recent history suggests circulation in France.