The researchers were able to piece together synthetic poliovirus DNA, then use an enzyme to transcribe it into viral RNA--which then, according to Wimmer, "functioned like real viral RNA" and made proteins, ultimately forming infectious poliovirus. The man-made virus led to paralysis or death in mice engineered to carry the human receptor for poliovirus.

"This shows you can recreate a virus from written information," Wimmer told Reuters Health. The findings were published Thursday in Sciencexpress, the online edition of the journal Science.

Because of global vaccination efforts, most of the world is protected from polio ( news - web sites), and health officials say polio eradication is in sight. But even if the world is declared polio-free, the ability to synthesize poliovirus could pose a bioterror threat if mass polio vaccination were to end, according to Wimmer and his colleagues.

Polio infection itself causes paralysis or death in only a small percentage of people. But, Wimmer pointed out in an interview, it is also possible for other viruses, such as influenza, to be synthesized using only published information on the make-up of the bugs.

"One has to be aware that humans can recreate a virus," Wimmer said, "even if you think it's not around anymore"--as could become the case with poliovirus if it's eradicated.

According to the researcher, the fact that synthetic poliovirus can be made should be in health officials' minds as they decide how to deal with polio vaccination after the natural virus is considered eradicated.

"We're adding one more piece of data," he said, that polio vaccination should continue for some time after eradication.