Molecular detection of severe fever with thrombocytopenia syndrome virus in Korean domesticated pigs

Background: Severe fever with thrombocytopenia syndrome virus (SFTSV) is an emerging tick-borne virus in China, Japan, and Korea. Although the incidence of SFTS has been increasing annually since the first SFTSV case was reported in Korea, the prevalence of SFTSV in Korean livestock has not conducted. The purpose of this study was to investigate the prevalence of SFTSV in domesticated pigs (Sus scrofa domesticus) throughout Korea. Methods: A total of 240 sera were collected from 30 domesticated pigs in eight provinces. To detect SFTSV, one-step reverse transcription RT nested PCR was conducted using SFTSV genome-specific primer sets. The amplified PCR products were cloned and then sequenced. Results: Four of 240 (1.7%) pig sera tested positive for SFTSV through one-step RT nested PCR. Two of the four obtained sequences were included in the Japanese clade, whereas the other two sequences were related to the Chinese clade based on phylogenetic analysis. Moreover, the obtained SFTSV sequences from this study were distinct from human SFTSV strains. Conclusions: This study is the first to attempt the identification of SFTSV sequences from domesticated pigs and the first molecular detection of SFTSV in Korean livestock. Our findings indicate that a new subclade of SFTSV - different from that in humans - may be present in domesticated pigs; the surveillance of SFTSV in livestock is required to better understand the life cycle of SFTSV.