Alignment of amino acid residues of neutralizing antigenic (NAg) sites 1 (<i>VP1</i>: 88–106), 2 (<i>VP2</i>: 163–169; <i>VP2</i>: 268–270; <i>VP1</i>: 220–225), 3a (<i>VP3</i>: 54–61; <i>VP3</i>: 70–74; <i>VP1</i>: 286–291), and 3b (<i>VP2</i>: 71–73; <i>VP3</i>: 75–79) for Sabin 3, its parental strain Leon/USA/1937, <i>VP1</i> capsid recombinants, Sabin 2, and some wild-type polioviruses circulated worldwide after 1960 (GenBank accession numbers: EU918372, EU918375, EU918374, FJ914252, FJ842179, AM707037, AM707033, AY221236, AY189887, AY221231, AY221227, AY221224, and AY741367).

<p>The rectangle shows NAg3a displacement in VP1 from Sabin 3 to Sabin 2 due to the recombination. The dashed rectangle shows NAg3a of type 3 wild polioviruses circulated after 1980.