Thiol-based chemical probes exhibit antiviral activity against SARS-CoV-2 via allosteric disulfide disruption in the spike glycoprotein

This study reports the discovery and mechanistic characterization of thiol-based chemical probes that inhibit SARS-CoV-2 infection by disrupting the viral spike protein’s binding to ACE2. The authors screened a library of cysteine-targeted electrophiles and identified compounds that covalently modify cysteine residues at the receptor-binding interface of the spike receptor-binding domain (RBD). These modifications reduce the binding affinity between spike and ACE2, thereby limiting viral entry into host cells. In vitro assays confirmed potent antiviral activity against both wild-type and variant viruses, with minimal cytotoxicity in host cells. Biophysical and mass spectrometric analyses validated the covalent adduct formation at specific cysteines in spike. The work demonstrates how redox-reactive, covalent chemical tools can be harnessed to perturb viral-host interactions and highlights cysteine targeting as a promising antiviral strategy. This approach may broadly apply to other viral systems with exposed reactive cysteines at critical interaction surfaces.