Detection and Genetic Analysis of Songling Virus in Haemaphysalis concinna near the China-North Korea Border

Abstract

Background: Songling virus (SGLV) is a spherical, enveloped, fragmented, negative-stranded RNA virus belonging to the genus Orthonairovirus in the Nairoviridae family. SGLV is transmitted by ticks and can cause disease in humans. This study identified and characterized SGLV in Haemaphysalis concinna ticks collected in 2023 in the Yanbian Korean Autonomous Prefecture (China) near the China-North Korea border. Methods: A real-time quantitative polymerase chain reaction (RT-qPCR) was used to screen for SGLV nucleic acid in ticks. Baby hamster kidney (BHK-21) and African green monkey kidney (Vero) cells were used to isolate strains of SGLV from nucleic acid-positive samples through three successive passages. Next-generation sequencing and phylogenetics methods were used to characterize the SGLVs. Results: Of the 1659 ticks collected from 6 towns in the Yanbian Korean Autonomous Prefecture near the China-North Korea border, positive SGLV nucleic acid results were identified in 19 H. concinna tick pools from Helong and Longjing towns. This discovery led to the extraction of 17 SGLV genome sequences. Homology analysis that compare the newly discovered L, M, and S segments of SGLV strain HLJ1202 revealed nucleotide similarities ranging from 95.5%–97.1%, 91.9%–98.9%, and 98.3%–99.2%, respectively, and amino acid similarities ranging from 95.7%–97.4%, 97.1%–98.8%, and 98.2%–98.9%, respectively. Six distinct clades, characterized by specific geographic locations and host organisms, were identified on the Maximum Likelihood tree of the L segment. The YB129 and YB150 isolates demonstrated SGLV nucleic acid replication across three successive passages in Vero cells, as evidenced by the decrease in RT-qPCR Ct values. Conclusion: This study marks the initial identification of SGLV in H. concinna within the Yanbian Korean Autonomous Prefecture.