The deadly coronavirus arrived by courier Feb. 6, delivered to a windowless, air-locked laboratory in a secret location on the University of North Carolina at Chapel Hill campus. It came sealed in two 500-microliter vials, wrapped inside plastic pouches, placed inside a third sealed plastic container, all packed with dry ice.A team of scientists — protected head-to-toe by Tyvek body suits with battery-powered respirators — opened the vials, got down to work and haven't stopped since.