With the help of powerful X-rays, researchers have determined the three-dimensional structure of a single giant virus particle. This shows how tiny objects that cannot be easily crystallized can still be imaged in 3D.

Credit: Tomas Ekeberg, Uppsala Univ

X-ray crystallography is commonly used to work out the structure of molecules, but these must be crystallized first. However, free-electron lasers generate such high-energy X-ray pulses that they can, in theory, produce pictures of just a single molecule.

Tomas Ekeberg at Uppsala University in Sweden and his colleagues fired these lasers at single particles of the Acanthamoeba polyphaga mimivirus. They used algorithms to combine X-ray diffraction patterns (pictured) from many specimens and created a 125-nanometre-resolution image of the virus.

The results confirm that that the mimivirus is less densely packed with genetic material than smaller viruses tend to be.

Phys. Rev. Lett. 114, 098102 (2015)