Nucleotide sequence from neurovirulent and attenuated strains of type 3 poliovirus.

As part of an investigation into the molecular basis of attenuation in the Sabin poliovirus vaccines, the genomes of three strains of type 3 poliovirus differing in neurovirulence were cloned in Escherichia coli. The nucleotide sequence of the region of the genome encoding the virion protein 1 (VP1) polypeptide from each of these strains is presented. Very few changes were observed, a finding suggesting that the mutation(s) involved in the attenuation of type 3 poliovirus probably lies elsewhere in the genome. The complete nucleotide sequence of one of the strains, P3/Sabin, has been obtained and is compared with the published sequences of type 1 poliovirus. Between serotypes 1 and 3, there is 77% homology in nucleotide sequence and 90% homology in the amino acid sequence predicted for viral proteins.