Pyrimidine biosynthesis inhibitors synergize with nucleoside analogs to block SARS-CoV-2 infection

Schultz, David C.; Johnson, Robert M.; Ayyanathan, Kasirajan; Miller, Jesse; Whig, Kanupriya; Kamalia, Brinda; Dittmar, Mark; Weston, Stuart; Hammond, Holly L.; Dillen, Carly; Castellana, Lauren; Lee, Jae Seung; Li, Minghua; Lee, Emily; Constant, Samuel; Ferrer, Marc; Thaiss, Christoph A.; Frieman, Matthew B.; Cherry, Sara

The ongoing COVID-19 pandemic has highlighted the dearth of approved drugs to treat viral infections, with only ∼90 FDA approved drugs against human viral pathogens. To identify drugs that can block SARS-CoV-2 replication, extensive drug screening to repurpose approved drugs is underway. Here, we screened ∼18,000 drugs for antiviral activity using live virus infection in human respiratory cells. Dose-response studies validate 122 drugs with antiviral activity and selectivity against SARS-CoV-2. Amongst these drug candidates are 16 nucleoside analogs, the largest category of clinically used antivirals. This included the antiviral Remdesivir approved for use in COVID-19, and the nucleoside Molnupirivir, which is undergoing clinical trials. RNA viruses rely on a high supply of nucleoside triphosphates from the host to efficiently replicate, and we identified a panel of host nucleoside biosynthesis inhibitors as antiviral, and we found that combining pyrimidine biosynthesis inhibitors with antiviral nucleoside analogs synergistically inhibits SARS-CoV-2 infection in vitro and in vivo suggesting a clinical path forward.