Baculovirus-mediated production and purification of ferritin nanoparticles for rift valley fever vaccine development

Rift Valley fever (RVF) is a WHO-prioritized zoonotic, vector-borne disease with no licensed prophylaxis available for humans, highlighting the need for effective vaccine strategies. Nanoparticle-based platforms for antigen presentation offer a promising approach for vaccine development. In this work, we engineered ferritin (Ft) nanoparticles to display the immunogenic Gn domain of RVF virus (GnFt) and systematically assessed the production, purification, and physico-chemical properties of the purified nanoparticles. Baculovirus-based expression systems were evaluated in insect (Sf9, High-Five™, Tnao38, and Tnms42) and mammalian cells (HEK293 and CHO), revealing Sf9 cells as the most efficient host for producing GnFt nanoparticles. In addition, affinity-based chromatography was explored, yielding GnFt nanoparticles of > 95% purity (as assessed by SDS-PAGE) and an overall production yield of 0.2 mg/L culture. Biophysical characterization (e.g., high-performance liquid chromatography, dynamic light scattering, electron microscopy, and mass photometry) confirmed proper 24-mer nanoparticle assembly (1,344 kDa and 20 nm) and structural integrity. Binding affinity to Gn-targeting monoclonal antibodies was demonstrated by biolayer interferometry, with dissociation constants in the nM range, indicating retained antigenic functionality. These findings demonstrate the successful development of a platform for producing structurally stable, pure, and functional Gn-presenting ferritin nanoparticles, supporting their potential use for RVF vaccine development.