A total of 48 poliovirus genomes were used in this study ( Table 1 ). The serial number (SN), genotype, length value, isolated region, GenBank accession numbers, and other detail information about these strains were listed in Table 1 . All of the sequences were downloaded from NCBI http://www.ncbi.nlm.nih.gov/Genbank/, and 48 poliovirus genomes were selected in the study. The other sequences with >98% sequence identities were excluded.