Friday, October 26, 2007

When Viruses Attack


By: Kristen Philipkoski


It's not a lunar lander and it's not a new breed of killer mosquito. It's a very common bacteria-eating virus and researchers have a closer look at it now than ever before.
Researchers at Purdue University combined traditional crystallography and cryoelectron microscopy with imaging software to create detailed pictures of a virus called T4. The Purdue scientists also made a video that shows how the virus attaches to a cell surface, infects it and replicates.
The work isn't just visually impressive, it gives researchers insight into the T4 virus that could elucidate the secrets of viral infection and possibly improve gene-therapy techniques, the Purdue researchers said. Their work was published in the Aug. 20 issue of Cell.
"By changing the receptor molecule at the ends of the long tail fibers," said Michael Rossmann, a structural biologist at Purdue, "you may be able to target specific cells or add to the genome of the virus to get it to insert additional genes into target cells."
T4 is a bacteria-eating virus called a bacteriophage, or phage for short. The word "bacteriophage" was forged from "bacterium" combined with the Greek "phagein," to eat. Each phage eats just one specific type of bacteria. The T4 phage feasts on E-coli. Because overuse is rapidly rendering antibiotics ineffective, researchers are turning to phage viruses as possible replacements. Bacteriophage therapy has been used in Eastern Europe and Russia for decades, but antibiotics have been more popular in the West.
VideoWatch the animation of a virus infecting a cell.
Felix d'Herelle of the Pasteur Institute in France dubbed the bacteria-eaters bacteriophages in 1917. They're one of the simplest life forms on Earth, with a head made of DNA, and spidery legs that grab the bacterium. The video shows how T4 latches on to E-coli with its seven appendages and injects the bacteria with its DNA. Next, it will make copies of itself, eventually causing the E-coli to explode, launching hundreds of new phage particles into the area.
Honing this process into a successful gene therapy is likely decades away. But Rossmann and his colleagues continue their research primarily for the thrill of gaining knowledge.
"In research, one question always leads to the next question," he said. "We may stop working on a particular virus, but there's always one around the corner."

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