Our DNA is littered with the absorbed remnants of ancient viruses, which normally are considered little more than genomic junk. But in a Frankenstein-like maneuver, French molecular geneticists led by Thierry Heidmann of the Gustave-Roussy Institute have now reassembled one of these long-lost retroviruses into its original infectious form.
Relics of the retrovirus are scattered throughout our genome but have long since lost their infectivity due to mutation. By comparing 10 or so of these dysfunctional relics, Heidmann and his colleagues puzzled out the components of the original virus that must have infected our ancestors eons ago. Using DNA cloning techniques, they then reconstructed a version that can infect human cells. Heidmann says this virus, which he calls Phoenix, is completely harmless. But he thinks it could play a role in cancer research because high levels of similar retroviral particles have been found in many different types of tumors, leading oncologists to suspect that they may help cancers grow.
Others say the experiment isn't likely to yield practical applications and that Heidmann's work is really just a proof-of-concept stunt that should have been subject to international oversight. "No one is going to be making a bioweapon out of this," admits Rutgers University molecular biologist Richard Ebright. But he also points out that until the retrovirus was reconstructed, its infectivity "could not be known and could not be unequivocally predicted." Moreover, he adds, there are no U.S. laws guarding against the re-creation of controlled human pathogens other than smallpox. The guidelines that exist are voluntary, and researchers are not formally monitored. Poliovirus, the 1918 flu virus, and now this previously extinct retrovirus have all recently been assembled in the laboratory. "It is well past due for some form of oversight to be put in place," Ebright says.