Development of anti-Gn monoclonal antibodies for magnetic nanoparticle-coupled lateral flow detection of severe fever with thrombocytopenia syndrome virus

Severe fever with thrombocytopenia syndrome virus (SFTSV) is an emerging tick-borne zoonotic pathogen associated with high mortality in humans and silent circulation in animals, highlighting the need for rapid, field-deployable diagnostics. Current molecular and serological methods remain dependent on specialized infrastructure, limiting their use in resource-limited settings. Here, we developed a magnetic nanoparticle-enhanced lateral flow assay targeting the SFTSV glycoprotein Gn (Gn-LFA) for rapid antigen detection. A panel of anti-Gn monoclonal antibodies was generated and systematically characterized for isotype, epitope recognition, binding affinity, and viral capture efficiency. A monoclonal antibody exhibiting strong Gn recognition and antigen-capturing activity was selected as the detection antibody and conjugated to magnetic nanoparticles, while three additional antibodies were used as capture antibodies on the test line to improve antigen recognition. The Gn-LFA detected recombinant Gn proteins produced in both mammalian and plant expression systems and demonstrated compatibility across sera from multiple host species. The assay detected as little as 20 ng of recombinant Gn protein or approximately 5 × 10 5 FFU of SFTSV within 45 min without requiring specialized instrumentation. Collectively, this study provides proof of concept for a rapid and low-cost approach to SFTSV antigen detection and supports its further development for potential applications in resource-limited settings and One Health surveillance.