Cover photograph (Copyright © 1999, American Society for Microbiology. All rights reserved.): Three-dimensional structure of the herpes simplex virus type 1 virion as determined by electron cryomicroscopy and computer reconstruction. The map, which is color-coded according to the particle radius, reveals the 1,250-Å wide icosahedral capsid and the icosahedrally ordered tegument proteins (purple) attached to the penton regions. A portion of the mass density of the map is removed to show the concentric shells of density (red orange) inside the capsid, spaced 26 Å apart, which are attributed to be the double-stranded DNA. (See related article on page 3210.)