Professor Kay Grunewald tells us how structural cell biology can help us understand virus infection. Cells constitute the smallest autonomous units of life. The tightly regulated structural and functional organisation is currently only rudimentary understood. Professor Kay Grünewald uses electron cryotomography in combination with other techniques to analyse virus' 'life cycle' in situ, which requires an understanding of its transient structures at the molecular level. Imaging techniques allow us to understand the communication between the virus and the components of the cell it is infecting, which can ultimately help to treat infectious diseases. Creative Commons Attribution-Non-Commercial-Share Alike 2.0 UK: England & Wales; http://creativecommons.org/licenses/by-nc-sa/2.0/uk/