An enhanced broad-spectrum peptide inhibits Omicron variants in vivo

The continual emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern (VOCs) poses a major challenge to vaccines and antiviral therapeutics due to their extensive evasion of immunity. Aiming to develop potent and broad-spectrum anticoronavirus inhibitors, we generated A1-(GGGGS)7-HR2m (A1L35HR2m) by introducing an angiotensin-converting enzyme 2 (ACE2)-derived peptide A1 to the N terminus of the viral HR2-derived peptide HR2m through a long flexible linker, which showed significantly improved antiviral activity. Further cholesterol (Chol) modification at the C terminus of A1L35HR2m greatly enhanced the inhibitory activities against SARS-CoV-2, SARS-CoV-2 VOCs, SARS-CoV, and Middle East respiratory syndrome coronavirus (MERS-CoV) pseudoviruses, with IC50 values ranging from 0.16 to 5.53 nM. A1L35HR2m-Chol also potently inhibits spike-protein-mediated cell-cell fusion and the replication of authentic Omicron BA.2.12.1, BA.5, and EG.5.1. Importantly, A1L35HR2m-Chol distributed widely in respiratory tract tissue and had a long half-life (>10 h) in vivo. Intranasal administration of A1L35HR2m-Chol to K18-hACE2 transgenic mice potently inhibited Omicron BA.5 and EG.5.1 infection both prophylactically and therapeutically. [Display omitted] •A1L35HR2m is a broad-spectrum SARS-CoV-2 fusion inhibitor with enhanced activity•A1L35HR2m binds to SARS-CoV-2 HR1 with high affinity and exhibits α-helical structure•A1L35HR2m-Chol broadly and potently inhibits coronaviruses in vitro and in vivo•A1L35HR2m-Chol shows robust efficacy against current and emerging SARS-CoV-2 variants Bi et al. developed A1L35HR2m-Chol, a lipopeptide for pan-coronaviral inhibition, showing potent in vitro inhibitory activity against SARS-CoV-2 VOCs and closely related viruses. In vivo, A1L35HR2m-Chol also demonstrates robust prophylactic and therapeutic efficacy against SARS-CoV-2 variants.