mRNA-delivered neutralizing antibodies confer protection against SARS-CoV-2 variant in the lower and upper respiratory tract

Monoclonal antibodies (mAbs) have been developed as effective biological countermeasures against a range of human diseases. The high cost of antibody production and manufacturing limits its clinical application and widespread use. The mRNA-lipid nanoparticle (mRNA-LNP) is a versatile platform for development of vaccines and protein-replacement therapeutics. Since the COVID-19 pandemic, a number of neutralizing mAbs against SARS-CoV-2 have been identified with several being used clinically under emergency authorization. Herein, we report the design and generation of mRNA-LNPs expressing two SARS-CoV-2 neutralizing mAbs, 76E1 and LY1404, which respectively target the viral spike protein’s fusion peptide (FP) epitope within the S2 subunit and the receptor-binding domain (RBD) within the S1 subunit. We show a single intramuscular administration of mRNA-LNPs results in efficient LY1404 and 76E1 mAb production in mice which is sustained for 7-14 days. Further, we evaluate the protective efficacy of mRNA-LNP formulations encoding the two antibodies in mouse and hamster models challenged with different SARS-CoV-2 viral strains. The data demonstrate that a single administration of mRNA-LNP encoding the more broadly neutralizing antibody 76E1 confers significant protection against the immune-evasive SARS-CoV-2 Omicron variant BQ.1 in both the upper and lower respiratory tract of the hamsters, indicating its potential impact on limiting both viral disease and viral acquisition. Together, our study highlights the potential of the mRNA-LNP platform to deliver therapeutic antibodies for rapid prevention or treatment of pathogenic infections.