New technology looks inside live viruses

WASHINGTON, USA: Scientists have developed a new technique which uses cutting edge technology to peer inside living viruses, the tiniest among micro-organisms, says a study.

The technique combines cryo-electron microscopy (cryo-EM) -- cutting-edge microscopy with 3D computer imaging -- to image the internals of a virus no bigger than 15 and 200 nanometres. A nanometre is a billionth of a metre.

Cryo-EM by itself does not help visualize internal structures of the micro-organism, because radiation is used to image them. But by tweaking the process with computers, imaging is possible.

"With lower doses of radiation, it is not possible to see inside the organism," said study author Alasdair Steven of the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS).

"However, higher doses of radiation damage the virus, destroying the very structures that we would like to view," said Steven, the journal Science reported.

Working with researcher Lindsay Black at the University of Maryland Medical School, Baltimore, Steven and his team were able to turn the problem of radiation damage into an asset, according to a university statement.

They realized that proteins inside the virus are more sensitive to damage than DNA.

"We first used low doses of radiation and recorded images in which the inner structure of the virus was invisible," said Steven.

"Next, we used high doses of radiation, and found that the inner structure could be seen as a cylinder of bubbles," he added.

While the inner structure was damaged, the team was able to superimpose the images, using 3D computer reconstruction.

As a result, they were able to clearly visualize the viral structure. The investigators termed this technique as bubblegram imaging.