Multivalent bicyclic peptides are an effective antiviral modality that can potently inhibit SARS-CoV-2.

COVID-19 has stimulated the rapid development of new antibody and small molecule therapeutics to inhibit SARS-CoV-2 infection. Here we describe a third antiviral modality that combines the drug-like advantages of both. Bicycles are entropically constrained peptides stabilized by a central chemical scaffold into a bi-cyclic structure. Rapid screening of diverse bacteriophage libraries against SARS-CoV-2 Spike yielded unique Bicycle binders across the entire protein. Exploiting Bicycles' inherent chemical combinability, we converted early micromolar hits into nanomolar viral inhibitors through simple multimerization. We also show how combining Bicycles against different epitopes into a single biparatopic agent allows Spike from diverse variants of concern (VoC) to be targeted (Alpha, Beta, Delta and Omicron). Finally, we demonstrate in both male hACE2-transgenic mice and Syrian golden hamsters that both multimerized and biparatopic Bicycles reduce viraemia and prevent host inflammation. These results introduce Bicycles as a potential antiviral modality to tackle new and rapidly evolving viruses

Multivalent bicyclic peptides are an effective antiviral modality that can potently inhibit SARS-CoV-2.

Acknowledgements: This work was supported by the MRC (UK; U105181010), a Wellcome Trust Investigator Award (223054/Z/21/Z), a Wellcome Trust Collaborator Award (214344/A/18/Z) and Innovate-UK (UKRI Ideas to Address COVID-19 – Innovate UK Article 25 funding strand). AO and JPS acknowledge funding from EPSRC, Unitaid, Wellcome Trust and MRC for funding which supported development of preclinical models for SARS-CoV-2 infection. We would like to thank Viroclinics Xplore for in vivo studies, Evotec for contract research services, Rachel Dods and Gustavo Arruda Bezerra for structural analysis, Radu Aricescu for design of lentiviral S protein expression systems, Andrew Carter for cloning of S-pseudotyped vectors, Dean Clift for Incucyte analysis, Tyler Rhinesmith and Jakub Laptuk for cell culture and assay support and the Bicycle team and James lab for general scientific support.COVID-19 has stimulated the rapid development of new antibody and small molecule therapeutics to inhibit SARS-CoV-2 infection. Here we describe a third antiviral modality that combines the drug-like advantages of both. Bicycles are entropically constrained peptides stabilized by a central chemical scaffold into a bi-cyclic structure. Rapid screening of diverse bacteriophage libraries against SARS-CoV-2 Spike yielded unique Bicycle binders across the entire protein. Exploiting Bicycles' inherent chemical combinability, we converted early micromolar hits into nanomolar viral inhibitors through simple multimerization. We also show how combining Bicycles against different epitopes into a single biparatopic agent allows Spike from diverse variants of concern (VoC) to be targeted (Alpha, Beta, Delta and Omicron). Finally, we demonstrate in both male hACE2-transgenic mice and Syrian golden hamsters that both multimerized and biparatopic Bicycles reduce viraemia and prevent host inflammation. These results introduce Bicycles as a potential antiviral modality to tackle new and rapidly evolving viruses