Three-dimensional visualization of tegument/capsid interactions in the intact human cytomegalovirus

The three-dimensional structure of the intact human cytomegalovirus (HCMV) was determined to 18-Angstrom resolution by electron cryomicroscopy and com puter reconstruction. Its capsid shell is composed of pentons, hexons, and triplexes arranged on a T = 16 icosahedral lattice and is identical to that of the B-capsid isolated from host cell nuclei. An icosahedrally ordered t egument layer formed by 960 copies of filamentous density is also visualize d, which interacts with the pentons, herons, and triplexes of the underlyin g capsid. The observed structural similarities and differences of HCMV with those of herpes simplex virus offer insights into the significance of the different tegument components for their infection processes while maintaini ng similar capsids. (C) 1999 Academic Press.