Nucleotide sequences of the VP1 capsid proteins of wild poliovirus types 1 and 3 from epidemic areas of Brazil.

The nucleotide sequences encoding the capsid protein VP1 were determined for the wild polioviruses of serotypes 1 and 3 endemic to the northeastern region of Brazil. Compared with the corresponding Sabin vaccine strain sequences, the wild isolates differed at 20% (type 1) and 22% (type 3) of their nucleotide positions, and in 7% (type 1) and 11% (type 3) of their amino acid residues. The highest degree of amino acid heterogeneity occurred within the amino-terminal residues of the VP1 proteins. Intratypic amino acid differences also occurred in VP1 surface residues that form parts of antigenic sites for neutralizing antibodies.