FIG. 1.

Models for anterograde transport of HSV capsids and glycoproteins in axons and for the assembly at axonal termini. (A) Capsids (red) are transported on axonal microtubules (blue) separately from vesicles containing HSV glycoproteins (green). Subsets of the tegument proteins (not shown) are likely associated with capsid surfaces, while other tegument proteins associate with glycoproteins. (B) HSV virions composed of capsids, tegument proteins, and an envelope including viral glycoproteins are transported within vesicles that are bound onto microtubules. (C) HSV capsids surrounded by a lipid membrane that lacks the viral glycoproteins are transported separately from vesicles containing the viral glycoproteins. (D) At axon termini, capsids (coated with tegument proteins) assemble by budding into vesicles containing viral glycoproteins, producing a virion within a lipid vesicle. Fusion of the lipid vesicle with the plasma membrane releases virions (onto the surface of the neuron) that can then infect adjacent epithelial cells.