Surveillance and analysis of Haemaphysalis longicornis with SFTS virus in Tumen river basin located in the frontiers of Russia, Korea and Northeast China / 中华疾病控制杂志

ABSTRACT

Objective To mastered the distribution characteristics of Haemaphysalis longicornis in the Tumen River basin along the border between Russia, Korea and Northeast China, and understand the status of Haemaphysalis longicornis carrying the virus of fever with thrombocytopenia syndrome (SFTS), then, isolate the virus and analyze its genetic characteristics. Method Ticks were collected from Hunchun, Tumen, Helong and Longjing cities in the Tumen River basin of Jilin Province from April to September, 2017. Haemaphysalis longicornis was selected and grouped. SFTS virus was detected by real-time quantitative polymerase chain reaction (RT-qPCR). Virus isolation was carried out in Vero cells, besides, S,M,L gene segments were amplified . The homology of S, M and L gene segments was compared, phylogenetic tree was established, and their gene characteristics were analyzed. Result Haemaphysalis longicornis mainly distributed in Hunchun and Tumen City in the lower reaches of Tumen River. It was the dominant species in the two counties, reaching 71.85% and 87.62% respectively. A virus named YBHC-TICK2-2017/CHINA was isolated from Haemaphysalis longicornis collected in Hunchun. The sequences of S segment (1 746 bp), M segment (3 336 bp) and L segment (6 376 bp) of the virus were 98.00%-99.00%, homologous to those of SFTS virus isolates from China and Korea recorded in National Center for Biotechnology Information (NCBI) Gen Bank. Phylogenetic tree analysis showed that the S segment gene sequence of the virus strain was divided into a cluster with Jilin strain (KT890282) in China, and M segment and L segment gene sequence with Jiangsu strain (KR230781) in China. Conclusions Haemaphysalis longicornis are widely distributed in the lower reaches of the Tumen river. It was the first time that SFTS virus was isolated from Haemaphysalis longicornis in this area, suggesting that this area is important for SFTS prevention.