Abstract

It was announced on 11 July that infectious poliovirus cDNA had been synthesised de novo in a laboratory for the first time (1). Scientists synthesised full length poliovirus cDNA by assembling oligonucleotides of plus and minus strand polarity, and then transcribed them into viral RNA with RNA polymerase. The viral RNA was translated and the synthesis of infectious poliovirus replicated. Transgenic mice injected intracerebrally with this virus developed flaccid paralysis or death, resembling the disease caused by wild poliovirus. The results confirm that the paralysis was caused by the synthetic virus, although a larger inoculum of the synthetic virus was needed to cause paralysis than was the case for wild virus.