VOA常速英语:High-Tech Images Show How Viruses Infect Cells

HOUSTON — As people around the world contend with illnesses caused by viruses, including this year's strain of the flu or influenza, researchers continue to study how viruses work and how they manage to invade living cells in everything from bacteria to human organs. University of Texas researchers recently collaborated on an innovative technique that allowed them to see a virus in the act of infecting a cell.

At the University of Texas Medical School at Houston, Jun Liu uses a powerful electron microscope to examine E. coli bacteria and the tiny T-7 virus that infects them.

Liu says until now, scientists could only speculate on how this virus injected its genetic material into another cell, because it happens in an instant.

“Before they inject in, they do not have a channel. After they inject in, they actually degrade the channel, so you never have a chance to see it,” Liu said.

But in a collaborative study with other University of Texas colleagues, Liu used the electron microscope to examine quick-frozen solutions full of bacteria and viruses.

“Because when you freeze it, it is kind of like a snapshot that captures some intermediate stage. This is one of the highlights of this study, because we captured this intermediate stage that nobody had seen before,” Liu said.

This sophisticated technology was applied to a particular virus in this study, but what the researchers found could be useful in studying other viruses in the future, viruses that cause many diseases, such as influenza, or AIDS.

That is the hope of study participant Ian Molineux, professor of biology at the University of Texas main campus in Austin, who prepared the virus samples used in the study.

“If we can find a way of blocking any of multiple steps towards the final internalization of the genetic material, it provides the potential for finding more anti-viral drugs,” Molineux said.

An animation, produced for Science magazine by the American Association for the Advancement of Science, shows how the virus puts out tendrils to, in effect, “walk” on the cell surface.

"Then it stops moving and all the legs come down and get fixed on the cell surface, and the infection begins to initiate," Molineux said.

Molineux says the collaborative effort with Liu and others paid off, with each member of the team bringing his own area of expertise into play.

“We have a very strong collaboration. We are looking at other viruses now,” Molineux said.

He says each advance in understanding how viruses function brings researchers closer to finding ways to defeat them - and save lives.