Three-Dimensional Structure of Herpes Simplex Virus from Cryo-Electron Tomography

TLDR

Herpes simplex virus is a complex DNA virus composed of a nucleocapsid, a pleiomorphic tegument, and an envelope essential for infectivity. Cryo‑electron tomography revealed that the tegument forms an asymmetric cap with a ~35‑nm gap on one side, contains particulate substructures and actin‑like filaments, and that the envelope bears 600–750 glycoprotein spikes whose nonrandom distribution suggests functional clustering.

Abstract

Herpes simplex virus, a DNA virus of high complexity, consists of a nucleocapsid surrounded by the tegument—a protein compartment—and the envelope. The latter components, essential for infectivity, are pleiomorphic. Visualized in cryo–electron tomograms of isolated virions, the tegument was seen to form an asymmetric cap: On one side, the capsid closely approached the envelope; on the other side, they were separated by ∼35 nanometers of tegument. The tegument substructure was particulate, with some short actin-like filaments. The envelope contained 600 to 750 glycoprotein spikes that varied in length, spacing, and in the angles at which they emerge from the membrane. Their distribution was nonrandom, suggesting functional clustering.