Hamsters were challenged with either 10 PFU (~3 ID 99 ) HTNV i.m., 500 PFU (~1.5 ID 99 ) HTNV i.n., 1,000 PFU (~1 ID 99 ) PUUV i.m., or 1,000 PFU (~1.5 ID 99 ) PUUV i.n.