Neonatal mouse model reveals pathogenesis of Shanxi Tick Virus 2 isolated from Haemaphysalis longicornis.

Shanxi Tick Virus 2(SXTV2), a Tamdy group member of Orthonairovirus genus, Nairoviridae family, was initially identified through Next Generation Sequencing, with its pathogenicity and risk profile remaining unclear. This study reports the first successful isolation of SXTV2 from Haemaphysalis longicornis ticks collected from Hunchun City, China-a tri-border region between China, Russia, and North Korea. The isolated SXTV2 strain replicated and produced cytopathic effects in both Vero (primate) and SW-13 (human) cell lines. Electron microscopy revealed that SXTV2 particles are enveloped, surface-spiked, pleomorphic, and approximately 100 nm in diameter. Experimental inoculation in neonatal mice led to significant weight loss, liver injury and 100% mortality. In conclusion, this study marks the first successful isolation of the SXTV2 strain and exploring the animal model for member of Tamdy group orthonairovirus. These findings suggest the need for enhanced surveillance of SXTV2 zoonotic exposure and disease epidemic risks.