Metagenomic Analysis of Mosquito-Borne Viruses in the Chinese Border Region at the China-North Korea-Russia Tri-border Area

The Tumen River basin, located at the tri-border region of China, North Korea, and Russia, is a hotspot for mosquito-borne diseases.However, research regarding mosquitoes as vectors and their viruses remains understudied.This study aims to elucidate the composition and distribution patterns of mosquito-borne viruses in this basin.From April to July 2025, 6,310 mosquitoes were collected in the four areas of the Tumen River basin by using mosquito traps.Viral metagenomics were confirmed by PCR and Sanger sequencing to identify the virus.We identified six mosquito viruses: Songling virus (SGLV), Daeseongdong virus 2 (DSDV2), Hubei mosquito virus 2 (HMV2), Yongsan picorna-like virus 3 (YPLV3), Yongsan picorna-like virus 4 (YPLV4), and Yichang virus (YCV).PCR results show that the minimum infection rates (MIR) for SGLV in Longjing mosquitoes were 25.02 per 1,000 mosquitoes; in Hunchun, the MIRs for YPLV3, YPLV4, YCV, HMV2, and DSDV2 were 1.61, 0.80, 1.61, 29.74, and 7.23 per 1,000 mosquitoes, respectively; and the MIR for YCV detected in Helong was 2.61 per 1,000 mosquitoes.This paper reports the first case of a new zoonotic virus strain in China, SGLV, and determines that it is highly concentrated in local mosquito species.The detection of SGLV RNA in field-collected mosquitoes reflects viral presence in the local ecological setting, although whether this represents transient blood-meal remnants, mechanical carriage, or active infection remains an unverified hypothesis.Phylogenetic analysis revealed high sequence homology of SGLV and DSDV2 with isolates reported from other Eurasian countries, suggesting a broad geographic and transcontinental distribution of these viral lineages.The cross-host transmission potential of HMV2 and co-circulation with picorna-like viruses suggest the need for continued surveillance of these emerging insect-associated viruses.The above results have reduced the knowledge gap in the distribution patterns and genetic diversity of new arboviruses and provided support for building an effective crossborder surveillance system.