The complete 7,441-nucleotide sequence of the attenuated poliovirus Sabin 1 strain genome was determined, revealing 57 base substitutions compared to the virulent Mahoney strain.
The identification of mutations in the VP1 coding region of the Sabin 1 strain suggests these changes contribute to viral attenuation.
The complete nucleotide sequence of the genome of the type 1 poliovirus vaccine strain (LSc,2ab) was determined by using molecular cloning and rapid sequence analysis techniques. The restriction fragments of double-stranded cDNA synthesized from the vaccine strain RNA were inserted into the adequate sites of cloning vector pBR322. Sequence analysis of the cloned DNAs revealed that the virion RNA molecule was 7,441 nucleotides long and polyadenylylated at the 3' terminus. When the nucleotide sequence was compared with that of the genome of the virulent parental strain (Mahoney), 57 base substitutions were observed to be scattered all over the genome. Of these, 21 resulted in amino acid changes in a number of viral proteins. A cluster of amino acid changes is located in the viral coat proteins, especially in the NH2-terminal half of the viral capsid protein VP1. These results may imply that the mutations in the VP1 coding region contribute to attenuation.
Nomoto et al. (1982) studied Poliovirus. Molecular cloning and sequence analysis vs. Virulent parental strain (Mahoney) was evaluated on Nucleotide sequence and mutation sites. The complete 7,441-nucleotide sequence of the attenuated poliovirus Sabin 1 strain genome was determined, revealing 57 base substitutions compared to the virulent Mahoney strain.