Identification\nof Potent, Broad-Spectrum Coronavirus\nMain Protease Inhibitors for Pandemic Preparedness

The COVID-19 pandemic highlights the ongoing risk of\nzoonotic transmission\nof coronaviruses to global health. To prepare for future pandemics,\nit is essential to develop effective antivirals targeting a broad\nrange of coronaviruses. Targeting the essential and clinically validated\ncoronavirus main protease (M<sup>pro</sup>), we constructed a structurally\ndiverse M<sup>pro</sup> panel by clustering all known coronavirus\nsequences by M<sup>pro</sup> active site sequence similarity. Through\nscreening, we identified a potent covalent inhibitor that engaged\nthe catalytic cysteine of SARS-CoV-2 Mpro and used structure-based\nmedicinal chemistry to develop compounds in the pyrazolopyrimidine\nsulfone series that exhibit submicromolar activity against multiple\nM<sup>pro</sup> homologues. Additionally, we solved the first X-ray\ncocrystal structure of M<sup>pro</sup> from the human-infecting OC43\ncoronavirus, providing insights into potency differences among compound–target\npairs. Overall, the chemical compounds described in this study serve\nas starting points for the development of antivirals with broad-spectrum\nactivity, enhancing our preparedness for emerging human-infecting\ncoronaviruses.