FIG. 2.

3D structure of the HHV-8 capsid at 24-Å resolution as viewed along the icosahedral twofold axis from the outside (A) and inside (B) of the capsid. The map was color coded according to the particle radius (see color bar at the bottom right), such that the upper domains of the pentons and hexons are in blue (between radii of 570 and 650 Å), the connecting triplexes are in green (between radii of 510 and 560 Å), the shell is in yellow (between radii of 460 and 510 Å), and the densities inside the capsid shell are in red (<460-Å radius). The capsid has a T=16 icosahedral symmetry (3 of the 12 fivefold axes are labeled 5, and 1 of the 20 triangular faces is outlined by a red dashed line in panel A), with the unique structural components in one asymmetric unit labeled, following the nomenclature established for HSV-1 (41, 57). These components include one-fifth of a penton (labeled 5), two and one-half hexons (one P, one C, and one-half of an E), and five and one-third triplexes (one each of the Ta, Tb, Tc, Td, and Te triplexes and one-third of the Tf triplex). The inside view in panel B is the same as that in panel A except that the upper half of the capsid was computationally removed to show the cutaway side views of some of the triplexes (dashed red arrows) and the inner floor of the HHV-8 capsids. Dot-dashed lines indicate icosahedral five-, three-, and twofold axes, which pass through a penton channel, a Tf triplex, and an E hexon channel, respectively. The densities inside the capsid shells (red) lack structural information because they are not icosahedrally disposed and thus have been removed computationally in the right half of panel B to show the internal surface of the capsid shell.