Intranasal Drop of Multiplex RNA Therapy for SARS-CoV-2 Infections: Baicalein-Enhanced FEN1 Nuclease Cleaving as a Virus Buster

Although the acute phase of the SARS-CoV-2 pandemic has subsided, viral persistence and variant evolution continue to challenge existing antiviral strategies, which often exhibit strain-specific limitations. Here, we investigated an intranasal nanomedicine formulation comprising flap endonuclease 1 (FEN1) and a panel of hairpin-structured DNA probes (hpDNAs), which we designed to concurrently target the highly conserved nucleocapsid RNA and host-derived Cathepsin L mRNA. This dual-targeting approach aims to interfere with both viral genetic integrity and the host-dependent entry pathway. Replacing conventional siRNA/sgRNA with stable, economical hpDNAs may improve the practicality of nucleic acid-based antivirals. Additionally, the co-administration of the anti-inflammatory agent baicalein was examined to assess its potential to improve the nanomedicine's cellular biodistribution. Our portable intranasal drop, a multi-target treatment co-administered with baicalein, elicited a partial reduction in the viral load in mice infected with SARS-CoV-2, suggesting that this multi-target strategy may offer an alternative antiviral modality for further development.