Studying poliovirus with infectious cloned cDNA

The application of molecular cloning to the study of poliovirus is discussed. Initially cDNA clones representing the entire genome of poliovirus type 1 (Mahoney) were prepared. These molecular clones were used for determining the complete nucleotide sequence of the viral genome. Subsequently a single cDNA clone representing the entire poliovirus genome was constructed. When this cDNA clone was transfected into cultured mammalian cells, infectious poliovirus was produced. The transfection-derived poliovirus was identical to wild-type virus by several criteria, including RNase T1-oligonucleotide fingerprint and 5' end nucleotide sequence. The availability of infectious cloned cDNA should make possible new approaches to the study of poliovirus.