PLoS Biol. 7, e1000092 (2009)

Mimivirus was once mistaken for a bacterium owing to its shape and great size. Michael Rossmann of Purdue University in West Lafayette, Indiana, and his colleagues have now revealed the structure of this largest of known viruses. Enzymatic scrubbing of long fibres that extend from the viral capsid gave the researchers a new view. They reconstructed the icosahedral shape of the virus using cryogenic electron microscopy and atomic force microscopy.

Mimivirus is not as symmetrical as many other large, double-stranded DNA viruses, in part because of a 'starfish' feature that appears on one side. This feature may allow the virus to deliver its genome into host cells.