Background

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging tick-borne viral disease caused by the SFTS virus (SFTSV) from Bunyaviridae that is endemic in East Asia. However, the genetic and evolutionary characteristics shared between tick- and human-derived Korean SFTSV strains are still limited.

Methodology/Principal findings

In this study we identify, for the first time, the genome sequence of a tick (Haemaphysalis longicornis)-derived Korean SFTSV strain (designated as KAGWT) and compare this virus with recent human SFTSV isolates to identify the genetic variations and relationships among SFTSV strains. The genome of the KAGWT strain is consistent with the described genome of other members of the genus Phlebovirus with 6,368 nucleotides (nt), 3,378 nt, and 1,746 nt in the Large (L), Medium (M) and Small (S) segments, respectively. Compared with other completely sequenced human-derived Korean SFTSV strains, the KAGWT strain had highest sequence identities at the nucleotide and deduced amino acid level in each segment with the KAGWH3 strain which was isolated from SFTS patient within the same region, although there is one unique amino acid substitution in the Gn protein (A66S). Phylogenetic analyses of complete genome sequences revealed that at least four different genotypes of SFTSV are co-circulating in South Korea, and that the tick- and human-derived Korean SFTSV strains (genotype B) are closely related to one another. Although we could not detect reassortant, which are commonly observed in segmented viruses, further large-scale surveillance and detailed genomic analysis studies are needed to better understand the molecular epidemiology, genetic diversity, and evolution of SFTSV.

Conclusions/Significance

Full-length sequence analysis revealed a clear association between the genetic origins of tick- and human-derived SFTSV strains. While the most prevalent Korean SFTSV is genotype B, at least four different genotypes of SFTSV strains are co-circulating in South Korea. These findings provide information regarding the molecular epidemiology, genetic diversity, and evolution of SFTSV in East Asia.

中文翻译：

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来自韩国的血小板减少症候群病毒分离株的壁虱和人源性重度发热的分子基因组学表征

背景

患有血小板减少症候群（SFTS）的严重发烧是由东亚流行的Bunyaviridae的SFTS病毒（SFTSV）引起的新兴壁虱传播的病毒性疾病。但是，tick和人类来源的韩国SFTSV菌株之间共有的遗传和进化特征仍然有限。

方法/主要发现

在这项研究中，我们首次鉴定了来自壁虱（Haemaphysalis longicornis）的韩国SFTSV菌株（命名为KAGWT）的基因组序列，并将该病毒与最新的人类SFTSV分离株进行比较，以鉴定SFTSV菌株之间的遗传变异和关系。 。所述KAGWT株的基因组是与该属的其它成员的基因组中描述的一致白蛉在大（L），中（M）和小（S）段分别具有6,368个核苷酸（nt），3,378 nt和1,746 nt。与其他完全测序的人源韩国SFTSV菌株相比，KAAGWT菌株在同一片段中分离自SFTS患者的KAGWH3菌株在每个片段的核苷酸和推导的氨基酸水平上具有最高的序列同一性，尽管有一个独特之处Gn蛋白（A66S）中的氨基酸取代。对完整基因组序列的系统进化分析表明，在韩国，至少有四种不同的SFTSV基因型正在共同传播，而tick和人类来源的韩国SFTSV菌株（基因型B）彼此密切相关。尽管我们无法检测到分段病毒中常见的重配子，

结论/意义

全长序列分析显示壁虱和人源SFTSV菌株的遗传起源之间的明确关联。虽然韩国最流行的SFTSV是B型基因，但SFTSV菌株中至少有四种不同的基因型在韩国共同流行。这些发现提供了有关东亚SFTSV的分子流行病学，遗传多样性和进化的信息。