Genetic and pathogenic diversity of severe fever with thrombocytopenia syndrome virus (SFTSV) in South Korea.

Seok-Min Yun,Young Ki Choi,Min-Ah Yu,Su-Jin Park,Won-Ja Lee,Hye Won Jeong,Hyeok-Il Kwon,Young-Il Kim,Youngmee Jee,Kwang-Min Yu,Eun-Ha Kim,Sun-Whan Park,Jungsang Ryou,Joo-Yeon Lee

doi:10.1172/jci.insight.129531

Abstract

To investigate nationwide severe fever with thrombocytopenia syndrome virus (SFTSV) infection status, we isolated SFTSVs from patients with suspected severe fever with thrombocytopenia syndrome (SFTS) in 207 hospitals throughout South Korea between 2013 and April 2017. A total of 116 SFTSVs were isolated from 3137 SFTS-suspected patients, with an overall 21.6% case fatality rate. Genetic characterization revealed that at least 6 genotypes of SFTSVs were co-circulating in South Korea, with multiple reassortments among them. Of these, the genotype B-2 strains were the most prevalent, followed by the A and F genotypes. Clinical and epidemiologic investigations revealed that genotype B strains were associated with the highest case fatality rate, while genotype A caused only one fatality among 10 patients. Further, ferret infection studies demonstrated varying clinical manifestations and case mortality rates with different strains of SFTSV, which suggests this virus could exhibit genotype-dependent pathogenicity.

Highlights

Severe fever with thrombocytopenia syndrome (SFTS) — an emerging tick-borne infectious disease with a high fatality rate and symptoms including severe fever and thrombocytopenia — was first reported in China in 2011 [1, 2]
The average case fatality rate varies among regions and years [13], the mean mortality rate of SFTS cases has remained relatively high in Japan (27%), South Korea (23.3%), and China (5.3%–16.2%) [10,11,12]
Due to the increasing incidence of human SFTS virus (SFTSV) infections, there is an elevated level of public concern

Summary

Introduction

Severe fever with thrombocytopenia syndrome (SFTS) — an emerging tick-borne infectious disease with a high fatality rate and symptoms including severe fever and thrombocytopenia — was first reported in China in 2011 [1, 2]. The average case fatality rate varies among regions and years [13], the mean mortality rate of SFTS cases has remained relatively high in Japan (27%), South Korea (23.3%), and China (5.3%–16.2%) [10,11,12]. The reason for the difference in mortality rates between countries and the mechanisms underlying the varied clinical manifestations caused by this infection are largely unknown; underlying disease conditions are suspected [17, 18]. Several studies reported the identification of at least 6 different genotypes of SFTSV in East Asian countries and that the prevalence of each genotype varied by country [19,20,21]

Methods

Results

Conclusion