Figure 8.

Incoming HSV-1 capsids display appendices at their vertices. At 1 h PI, Vero cells infected at an MOI of 500 in the presence of CH were extracted with 0.5% TX-100 in MT buffer for 2 min at 37°C and fixed in 1% GA in MT buffer. They were labeled with anti-tubulin followed by protein A–9 nm gold (a) or embedded directly (b–d), and Epon sections were cut parallel to the substrate. All viral capsids display some appendages on their outside (arrowheads). The appendages are visible at three, four, five, or all six corners visible in a section, which represent the pentons of a viral capsid. Some of the appendices have a morphology very similar to purified cytoplasmic dynein (large arrow in d): a large globular stalk with two smaller globular head domains. The capsid size is ∼100–110 nm; the dynein-like appendices are ∼50 nm. In thick sections of golden color, the appendices are often buried in cytoskeletal material (b and d), whereas in very thin sections of grey color (a and c), they are very prominent. The appendices have all kinds of different morphology with varying sizes and electron density, but they are always located at the pentons.