AT LEAST one virus that infects people may be able to hijack an ancient immune system that evolved to defend us against viral attacks.
When snippets of RNA are added to cells, a defence system called RNA interference shuts down any genes containing the same sequence. Thomas Tuschl of The Rockefeller University in New York wondered if human cells generated these RNAs when they are infected with the Epstein-Barr virus. To their surprise, he and his colleagues discovered that the virus itself makes at least five such microRNAs (Science, vol 304, p 734). Computer analysis suggests that these microRNAs silence both human and viral genes, helping the virus to exploit its host as well as to control its own life cycle.
It is not clear what role the microRNAs play in infection, or if other viruses produce them too. 鈥淚n some unrelated viruses we鈥檝e tested, we didn鈥檛 see anything like this,鈥� Tuschl says.
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