Currently, the structure of viruses are most accurate visualized using electron microscopy. Electron microscopy is considered to be a pretty outdated technology for many fields and uses; however, it remains at the forefront in the world of viruses. While electron microscopy can be useful for identifying particular viruses, the major drawback for the method is that it only provides a 2D image of the virus. For example, icosahedrally shaped virus capsids simply appear as hexagons under the microscope. While this type of image can be extremely useful to a trained eye, there is still much we can’t derive from this 2 dimensional image.
With the help of the Stanford Linac Coherent Light Source, researchers have mapped the structure of mimivirus. They did this by shooting powerful, and exceedingly short pulses of X-rays at the virus. So as not to understate this idea, each pulse lasted only 70 fs with a peak in power density that was more than 1018 times that of sunlight energy hitting earth. Not surprisingly, these X-rays destroyed the mimivirus particle, but before vaporization occurred, the virus caused the X-rays to scatter generating a recordable diffraction pattern. This technique can not only show the 3D external structure of the virus, but also allow researchers to observe the distribution of electrons inside the mimivirus particle.
The team is continuing to work to make this technique applicable to both larger and smaller particles, potentially allowing for the visualization of many of the human viruses we’ve studied over the course of the year.
- Eddie Irvine