| Three-dimensional reconstruction of large icosahedral viruses. Shown are images of herpes simplex virus type 1 capsids, which illustrate the potential of new parallel computing methods. They show the location of a minor capsid protein called VP26 as mapped in experiments in which VP26 was first extracted from purified capsids by treatment with guanidine hydrochloride and then rebound to the capsids. The right half of the top image shows the depleted capsid and the rebound VP26 capsid, and the left half shows the three- dimensional reconstruction, as it would be obtained with a conventional sequential computer. Parallel computing extended the analysis to obtain the lower images, which improved the signal-to- noise ratio and the resolution from approximately 3.5 to under 3.0 nanometers. The clusters of six VP26 subunits, shown together in the top image, are clearly resolved in the bottom image. This work was conducted at NIH in collaboration with the University of Virginia. |