Reversal of the progression of fatal coronavirus infection in cats by a broad-spectrum coronavirus protease inhibitor

This study tested a broad-spectrum coronavirus 3C-like protease inhibitor in cats with experimentally induced and naturally occurring FIP, showing that the drug could reverse progression of an otherwise fatal coronavirus infection. By inhibiting the protease that cleaves viral polyproteins into functional components, the compound blocked replication and allowed cats to recover. The work provided foundational proof that targeting a conserved coronavirus enzyme could treat lethal disease in a natural host, informing both feline therapeutics and the broader antiviral field. It matters because it bridged structure-based antiviral design and live-animal cure of a coronavirus disease, anticipating the importance of protease inhibitors that became prominent during later human coronavirus drug development.