DHODH and viral load: To test whether our potent DHODHi could refresh the important role of targeting DHODH in viral diseases, we next explored in vivo efficacy of S312 by intranasal infecting BALB/c mice at a lethal dose of WSN (2 LD50 = 4,000 PFU) or 2009 pandemic H1N1 (A/Sichuan/01/2009, SC09) (2 LD50 = 300 PFU) virus.