‘Sputnik’ Virus Can Attack Others, But Is it Alive?

August 11, 2008 11:30 AM
by Sarah Amandolare
The discovery of a virus that can infect other viruses has renewed discussion over whether viruses are living creatures and emphasized their important role in evolution.

The Mamavirus Is Born

Scientists have discovered the first virus capable of falling ill by being infected with another virus. This exciting twist has reignited the debate over whether viruses could be considered living things.

“The fact that it can get sick makes it more alive,” said virologist Jean-Michel Claverie of the Mediterranean Institute of Microbiology in Marseilles, France, where the virus was analyzed after being found in a cooling tower in Paris.

The scientists named the attacking virus Sputnik, and are calling it a virophage because it acts similarly to a bacteriophage—a virus that infects bacteria.

Sputnik’s victim is “one of a family of physically immense viruses, the first of which was isolated from a British cooling tower” in 2003 and dubbed a mimivirus. The size of this latest mimivirus is unprecedented, prompting researchers to name it a mamavirus.
According to virologist Eugene Koonin, a co-author of the findings of the study, the relationship between Sputnik and the mamavirus is a unique “host-parasite” pairing. “It’s the first time that these viruses have actually exchanged genes,” he said.

And Sputnik had a profound impact on the mamavirus. “The team found that cells co-infected with Sputnik produce fewer and often deformed mamavirus particles, making the virus less infective,” according to Nature News.

Presently, scientists and researchers are unsure of the significance of viral parasites, and whether the organisms could have an impact on the environment or human health. But according to Wired, “At the very least, it expands our idea of what is possible in the viral world.”

Background: Mimivirus

In March 2003, researchers in Marseille found a virus physically larger than any to that date and named it mimivirus because it mimics bacteria. The virus’ diameter and genetic composition were comparable to that of some bacteria, making the mimivirus the first of a new viral family.

“Mimivirus has many characteristics which put it at the boundary between living organisms and non-living entities,” including its size and genome characteristics, and genetic encoding capabilities. However, like all viruses, mimivirus particles reproduce by self-assembly, not division, differentiating them from live cellular organisms like bacteria.

Because the mimi is “so much more genetically complex than all previously known viruses,” Discover magazine explains, “it seems to call for a dramatic redrawing of the tree of life.” In other words, viruses could very well have been part of early evolution and a “formative force” in biology.

Reference: Viruses


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