Biology:SFTS virus
| Phleboviruses | |
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| Virus classification | |
| Group: | Group V ((−)ssRNA)
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| Order: | |
| Family: | |
| Genus: | |
| Species: | SFTS virus
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The SFTS virus is a tick-borne phlebovirus in the order Bunyavirales.[1] It appears to be more closely related to the Uukuniemi virus serogroup than to the Sandfly fever group.[1] It is a member of the Bhanja virus serocomplex.[2]
The clinical condition it caused is known as severe fever with thrombocytopenia syndrome (SFTS).[1] SFTS is an emerging infectious disease that was first described in northeast and central China and now has also been discovered in Japan and South Korea. SFTS has a fatality rate of 12% and as high as 30% in some areas. The major clinical symptoms of SFTS are fever, vomiting, diarrhea, multiple organ failure, thrombocytopenia (low platelet count), leukopenia (low white blood cell count) and elevated liver enzyme levels.
History
In 2009 Xue-jie Yu and colleagues isolated the SFTS virus (SFTSV) from SFTS patients’ blood.[1]
Genome
The genome has been sequenced.[1] There are three segments—large (L), medium (M) and small (S). Six proteins have been identified—an RNA dependent RNA polymerase (RdRp), a glycoprotein precursor (M), a glycoprotein N (Gn), a glycoprotein C (Gc), a nuclear protein (NP) and a non structural protein (NSs).
The L segment encodes the RNA polymerase with 2084 amino acid residues.
The M segment encodes one open reading frame encoding 1073 amino acid precursors of glycoproteins (Gn and Gc).
The S segment has 1744 nucleotides of ambisense RNA encoding two proteins, the N and NSs proteins. These lie in opposite orientations and are separated by a 62 nucleotide intergenic region.
Evolution
Five genotypes (A–E) have been identified.[3] Strains from China could be grouped into all five genotypes while isolates from South Korea lay in three (types A, D and E) and those from Japan only in one (type E). The virus appears to have originated in the Dabie Mountains in central China between 1918 and 1995.
Life cycle
SFTSV is a tick-borne virus; it is not clear whether it can be transmitted by other blood-sucking arthropods.[4] It can infect many mammalian hosts, including cats, mice, hedgehogs, weasels, brushtail possums and yaks. Humans appear to be accidental hosts, and play no essential role in the life cycle of SFTSV. SFTSV has been detected from the ixodid tick, Haemaphysalis longicornis, Ixodes nipponensis, Amblyomma testudinarium[5] and Rhipicephalus microplus.[6] In addition to tick bite, SFTSV can be transmitted from person to person through contact with blood or mucus of an infected person.[7][8]
Epidemiology
This virus has been found in the Chinese provinces of Anhui, Henan, Hubei, Jiangsu, Liaoning and Shandong. SFTS occurs in rural areas, from March to November, and a majority of cases are found from April to July.
The virus has also been found in South Korea and Japan.[9][10]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 "Fever with thrombocytopenia associated with a novel bunyavirus in China". N. Engl. J. Med. 364 (16): 1523–32. April 2011. doi:10.1056/NEJMoa1010095. PMID 21410387.
- ↑ "Characterization of the Bhanja serogroup viruses (Bunyaviridae): a novel species of the genus Phlebovirus and its relationship with other emerging tick-borne phleboviruses". J. Virol. 87 (7): 3719–28. April 2013. doi:10.1128/JVI.02845-12. PMID 23325688.
- ↑ "Molecular Evolution and Spatial Transmission of Severe Fever with Thrombocytopenia Syndrome Virus Based on Complete Genome Sequences". PLoS ONE 11 (3): e0151677. 2016. doi:10.1371/journal.pone.0151677. PMID 26999664.
- ↑ "Haemaphysalis longicornis Ticks as Reservoir and Vector of Severe Fever with Thrombocytopenia Syndrome Virus in China". Emerging Infect. Dis. 21 (10): 1770–6. October 2015. doi:10.3201/eid2110.150126. PMID 26402039.
- ↑ "Detection of SFTS Virus in Ixodes nipponensis and Amblyomma testudinarium (Ixodida: Ixodidae) Collected From Reptiles in the Republic of Korea". J. Med. Entomol. 53 (3): 584–590. May 2016. doi:10.1093/jme/tjw007. PMID 26957392.
- ↑ "The ecology, genetic diversity, and phylogeny of Huaiyangshan virus in China". J. Virol. 86 (5): 2864–8. March 2012. doi:10.1128/JVI.06192-11. PMID 22190717.
- ↑ "Person-to-person transmission of severe fever with thrombocytopenia syndrome virus". Vector Borne Zoonotic Dis. 12 (2): 156–60. February 2012. doi:10.1089/vbz.2011.0758. PMID 21955213.
- ↑ "A family cluster of infections by a newly recognized bunyavirus in eastern China, 2007: further evidence of person-to-person transmission". Clin. Infect. Dis. 53 (12): 1208–14. December 2011. doi:10.1093/cid/cir732. PMID 22028437.
- ↑ "Severe fever with thrombocytopenia syndrome, South Korea, 2012". Emerging Infect. Dis. 19 (11): 1892–4. November 2013. doi:10.3201/eid1911.130792. PMID 24206586.
- ↑ "The first identification and retrospective study of Severe Fever with Thrombocytopenia Syndrome in Japan". J. Infect. Dis. 209 (6): 816–27. March 2014. doi:10.1093/infdis/jit603. PMID 24231186.
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