As if the world isn't a dangerous enough place already, scientists decided that extinct is not forever, at least not for a retrovirus!
A team led by Thierry Heidmann at the Institut Gustave Roussy in Villejuif, France, near Paris, decided to try to awaken the ancestor of an entire family of HERVs called HERV-K(HML2). To "correct" for mutations, the researchers took dozens of known HERV-K(HML2) sequences and aligned them to create a so-called "consensus" sequence. Then they converted this information into a complete viral genome.
The researchers showed that the newly crated virus could infect a variety of human cell lines and replicate. But its infectivity was extremely low, perhaps because human cells have evolved resistance against such viral invaders.