Mass Spectrometry of an Intact Virus.

The simultaneous measurement of the time-of-flight and the number of charges on each electrosprayed ion provides a new way to determine the mass of a whole intact virus. The weights of an icosahedral virus (rice yellow mottle virus) consisting of a single-stranded RNA surrounded by a homogeneous protein shell with a mass of 6.5×106 Da, and a rod-shaped RNA virus (tobacco mosaic virus) with a mass of 40.5×106 Da were measured with this technique.