earticle

영어

Background. Dabie Bandavirus (SFTSV) is an emerging tick-bone infectious disease in eastern Asia. This virus causes thrombocytopenia syndrome with 12-30% fatality. However, the genetic diversity of SFTSVs and the associations between specific genotypes and clinical outcomes are poorly understood. Methods. We isolated SFTSVs from SFTS-suspected patients in 207 hospitals throughout South Korea between 2013 and April of 2017 to investigate the nationwide SFTSV infection status. Using the ferret animal model, we demonstrated the genotype- and age-dependent pathogenicities of SFTSVs. Results. A total of 116 SFTSVs were isolated from 3,137 SFTS-suspected patients with an overall 21.6% case fatality rate. Genetic characterization revealed that at least 15 genotypes of SFTSVs are co-circulating in South Korea with multiple reassortments among them. The genotype B strains were the most prevalent (69.4%, 93/134) followed by the A and F genotypes. Clinical and epidemiologic investigations revealed that genotype B strains were associated with the highest case-fatality rate (34.8%, 32/92), while genotype A caused only one case fatality out of ten patients. Further, ferret infection studies demonstrated age-dependent close associations among clinical manifestations, mortality rates, and genotypes of SFTSV. Conclusions. Due to active reassortment events, diverse genotypes of SFTSV are co-circulating in South Korea, with genotype B strains being most dominant. Clinical and experimental investigations revealed that the genotype B strains showed the highest case-fatality rate. These results suggest that the variation in SFTS mortality rates in different regions might be due to the prevalence of different SFTSV strains and age of patients.