Construction of an SFTSV ΔN reporter pseudovirus for antiviral drug screening

Severe fever with thrombocytopenia syndrome virus (SFTSV), also known as Dabie bandavirus (DBV), is an emerging zoonotic pathogen that poses a serious global public health threat. Experimental studies with live SFTSV require biosafety level 3 (BSL-3) or higher containment, which greatly restricts investigations into its infection mechanisms and the development of therapeutics and vaccines. To overcome these limitations, we constructed an NP-dependent conditional replication-deficient SFTSV ΔN pseudovirus (SFTSV ΔN pseudovirus) by replacing the nucleoprotein (NP) gene in the viral S segment with a reporter gene. Two versions of the ΔN genome were generated, carrying either the Gaussia luciferase (Gluc) or green fluorescent protein (GFP) reporter genes. Using a reverse genetics system, we successfully rescued SFTSV ΔN pseudovirus expressing these reporters. The resulting pseudoviruses can replicate only in cells or mouse tissues that provide Np in trans, thereby enhancing experimental safety. Utilizing the SFTSV ΔN-Luc reporter pseudovirus, we performed high-throughput antiviral drug screening and identified compounds, including sesamin, that effectively inhibited SFTSV replication. In conclusion, the SFTSV ΔN pseudovirus represents a powerful and safe platform for studying viral infection mechanisms, tissue tropism, and for screening antiviral candidates.