Deep sequencing and phylogenetic analysis of severe fever with thrombocytopenia syndrome virus from the tick,Haemaphysalis longicornis, in Korea

The Asian longhorned tick,Haemaphysalis longicornis, is widely distributed in China, Japan, and Korea and may transmit infectious diseases. Severe fever with thrombocytopenia syndrome (SFTS) is an important tick-borne disease caused by the SFTS virus (SFTSV). Deep sequencing to confirm the presence of SFTSV in ticks has not been reported in Korea. To detect SFTSV, RNA was extracted from tick samples and analyzed using high-throughput deep sequencing. Based on BLASTN results, numerous SFTSV reads were identified. Moreover, a nearly complete genome of SFTSV (JNU-1 isolate) was obtained using Sanger sequencing. The genome of the JNU-1 isolate includes three segments of 6,286, 3,299 and 1,642 nucleotides (nt) termed large (L), medium (M), and small (S), respectively. Also, phylogenetic and recombination analyses for each segment of SFTSV were performed using the JNU-1 isolate. The three segments of JNU-1 isolate were closely related to the genotype B known human-derived Korean SFTSV isolate; the JNU-1 isolate showed no recombination sites with other isolates. This study is the first report of detection of SFTSV from ticks using deep sequencing in Korea and provides information on the genetic diversity of SFTSV in East Asia.