Researchers from Emory University, the U.S. CDC and collaborators have identified a broad-spectrum antiviral agent able to combat highly pathogenic arenaviruses. The compound, a ribonucleoside analogue that acts through RdRp inhibition, exhibited a good pharmacokinetic profile, oral bioavailability and tissue distribution in guinea pigs, while protecting animals from lethal challenges with Lassa and Junín viruses, even at very low doses.