Metagenomic Analysis of Fever, Thrombocytopenia and Leukopenia Syndrome (FTLS) in Henan Province, China: Discovery of a New Bunyavirus

Abstract

Since 2007, many cases of fever, thrombocytopenia and leukopenia syndrome (FTLS) have emerged in Henan Province, China. Patient reports of tick bites suggested that infection could contribute to FTLS. Many tick-transmitted microbial pathogens were tested for by PCR/RT-PCR and/or indirect immunofluorescence assay (IFA). However, only 8% (24/285) of samples collected from 2007 to 2010 tested positive for human granulocytic anaplasmosis (HGA), suggesting that other pathogens could be involved. Here, we used an unbiased metagenomic approach to screen and survey for microbes possibly associated with FTLS. BLASTx analysis of deduced protein sequences revealed that a novel bunyavirus (36% identity to Tehran virus, accession: HQ412604) was present only in sera from FTLS patients. A phylogenetic analysis further showed that, although closely related to Uukuniemi virus of the Phlebovirus genus, this virus was distinct. The candidate virus was examined for association with FTLS among samples collected from Henan province during 2007–2010. RT-PCR, viral cultures, and a seroepidemiologic survey were undertaken. RT-PCR results showed that 223 of 285 (78.24%) acute-phase serum samples contained viral RNA. Of 95 patients for whom paired acute and convalescent sera were available, 73 had serologic evidence of infection, with 52 seroconversions and 21 exhibiting a 4-fold increase in antibody titer to the virus. The new virus was isolated from patient acute-phase serum samples and named Henan Fever Virus (HNF virus). Whole-genome sequencing confirmed that the virus was a novel bunyavirus with genetic similarity to known bunyaviruses, and was most closely related to the Uukuniemi virus (34%, 24%, and 29% of maximum identity, respectively, for segment L, M, S at maximum query coverage). After the release of the GenBank sequences of SFTSV, we found that they were nearly identical (>99% identity). These results show that the novel bunyavirus (HNF virus) is strongly correlated with FTLS.

Reverse Genetics System for Severe Fever with Thrombocytopenia Syndrome Virus

“…Importantly, the sequence data showed no evidence for an NSm protein upstream of the Gn-Gc precursor encoded by the M genome segment, which is a hallmark of the Uukuniemi virus group (13). The virus has been variously called DaBie Mountain virus (10,14), Henan fever virus (15), Huaiyangshan virus (16), and severe fever with thrombocytopenia syndrome virus (SFTSV) (10). The International Committee for Taxonomy of Viruses (ICTV) Executive Committee has recommended that the species name encompassing these viruses be SFTS virus, a proposal awaiting ratification by the ICTV membership.…”

Ulcerative Lesions with Hemorrhage in a Patient with Severe Fever with Thrombocytopenia Syndrome Observed via Upper Gastrointestinal Endoscopy

“…This disease was first reported to be endemic to China in 2011 (1,2), and later reported to be endemic to Japan and South Korea (3,4). Hemorrhagic symptoms such as gingival oozing, bloody diarrhea, and hematuria are commonly observed in patients with severe and fatal SFTS (3,5,6).…”

Detection of Severe Fever with Thrombocytopenia Syndrome Virus by Reverse Transcription–Cross-Priming Amplification Coupled with Vertical Flow Visualization

“…The virus, subsequently named severe fever with thrombocytopenia syndrome bunyavirus (SFTSV), is associated with a clinical syndrome characterized by fever, respiratory or gastrointestinal symptoms, thrombocytopenia, leukocytopenia, and hemorrhage in severe cases. SFTS has a mortality rate of around 12% and is believed to have existed for some time and to have a wide geographic distribution (9,13,16). The Haemaphysalis longicornis tick was found to carry SFTSV, suggesting that it is a possible vector of SFTSV infection to humans.…”