Identification of a new orthonairovirus associated with human febrile illness in China

The genus Orthonairovirus of the family Nairoviridae includes the important tick-transmitted pathogens, Crimean-Congo hemorrhagic fever virus (CCHFV) and Nairobi sheep disease virus (NSDV), as well as many other poorly characterized viruses isolated from ticks, birds, and mammals1,2. Here we identified a novel orthonairovirus, designated S[o]ngl[i]ng virus (SGLV), from patients who reported being bitten by a tick in China. The genome of SGLV shared similar structural features with orthonairoviruses, with 46.5-65.7% sequence identify. Phylogenetic analysis showed that SGLV belonged to the Tamdy orthonairovirus and formed a unique clade in the Nairoviridae family. Electron microscopy revealed typical morphological characteristics of orthonairoviruses. The isolated SGLVs from the blood samples of patients could induce cytopathic effects in human hepatoma cells. SGLV infection was confirmed in 42 patients in 2017-2018, with the main clinical manifestations of headache, fever, depression, fatigue and dizziness. Serological assays showed that 69% patients generated virus-specific antibody responses in the acute phase. In contrast, neither SGLV viral RNA nor specific antibodies against SGLV were detected in healthy individuals. SGLV was also detected in Ixodes crenulatus, Haemaphysalis longicornis, Haemaphysalis concinna, and Ixodes persulcatus in northeastern China. Collectively, a newly discovered orthonairovirus was shown to be associated with human febrile illness in northeastern China.