Sputnik then uses its genetic material to hijack the cellular machinery churning out copies of mimivirus and mamavirus, forcing them to make copies of Sputnik instead. As a result, the spread of mimivirus and mamavirus in the amoeba is slowed. Two organisms crammed into another creates a lot of free-floating genetic material. When scientists sequenced Sputnik's genome, they found traces of many different organisms, said Eugene Koonin, a researcher at the National Institutes for Health who worked with the French team. "Sputnik is a chimera. It has several genes that are distantly but clearly related to more familiar viruses, like pox viruses or the mimivirus or mamavirus," said Koonin. "Then again, it has some genes that are strange to see," he added. "It's very peculiar." Some of those peculiar genes come from archaea, a different branch of life altogether, but about 50 percent of Sputnik's genome was similar to marine viruses, leading scientists to speculate that Sputnik is not the only virus of its kind. "There are on average 50 million viruses in every milliliter of sea water," said Suttle, who studies marine viruses. "It's certainly possible that these viruses are very widespread." The viruses don't have any particular medical value yet, according to the scientists. They don't infect humans, and it is highly unlikely that doctors could modify Sputnik to parasitize viruses that attack humans, say both Koonin and Suttle. The scientists also dismiss discussions about whether the discovery is proof positive that viruses are alive, a debate that itself has refused to die. "It's a matter of semantics," said Koonin. "They are part of the biological world. They have their own genome. It depends on what your definition of alive is and what your preferences are." Alive or not, the discovery "shows just how little we know about the diversity of life," said Suttle. "It's an intriguing discovery." Related Links: |
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