How does a viral genome get into a viral capsid?

There are several strategies, but often the viral capsid is built first, leaving a pore open at one corner; and then the viral genome is fed into that pore, getting neatly wrapped up around scaffolding proteins like a spool of thread.

Herpesviruses follow that strategy, and here’s what it looks like for mouse herpesvirus 68. (This is just a little part of one image from a paper by the amazing Zhou lab [check out their animations!], whose gorgeous images I’ve shown before here.)

MHV68 DNA encapsidation

MHV68 capsid (green) with DNA (red) (1) feeding into the capsid (left); (2) being wrapped around the scaffold proteins (yellow; middle); and (3) almost completely wrapped (right)1

  1. Peng, L., Ryazantsev, S., Sun, R., & Zhou, Z. (2010). Three-Dimensional Visualization of Gammaherpesvirus Life Cycle in Host Cells by Electron Tomography Structure, 18 (1), 47-58 DOI: 10.1016/j.str.2009.10.017[]