By combining molecular biology and X-ray crystallography, Zihe Rao's research group resolved the crystal structures of the SARS-CoV main protease (SARS-CoV Mpro) interacting with a specific inhibitor; this was the first report of crystal structures of the SARS virus anywhere in the world. The three dimensional structures of SARS-CoV Mpro interacting with an inhibitor revealed an unexpectedly accurate mode of inhibitor binding and provided a structural basis for rational drug design.