The computationally designed TRI2-2 miniprotein inhibitor protects against multiple SARS-CoV-2 Omicron variants

The continued evolution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has compromised neutralizing antibody responses elicited by prior infection or vaccination and abolished the utility of most monoclonal antibody therapeutics. We previously described a computationally-designed, homotrimeric miniprotein inhibitor, designated TRI2-2, that protects mice against pre-Omicron SARS-CoV-2 variants. Here, we show that TRI2-2 exhibits broadly neutralizing activity of SARS-CoV-2 variants and protects mice against BQ.1.1, XBB.1.5 and BA.2.86 challenge when administered intranasally post-exposure. The resistance of TRI2-2 to viral escape by most variants and the ability to deliver it directly to the upper airways highlight the potential of the multivalent miniprotein inhibitor as an alternative therapeutic modality.