2.6 Phylogenetic analysis
The entire cap gene sequences (n=90) of the PiCV obtained in this study were used for phylogenetic analysis. All available PiCV sequence data from different geographical locations within China (n=54) and the rest of the world (n=72) were retrieved from the NCBI nucleotide database as reference sequences. Maximum likelihood phylogenetic trees were constructed with the GTR+G+I model implemented in the MEGA 5.0 software, with partial deletion to handle alignment gaps, and 1000 bootstrap iterations. The phylogenetic tree was annotated with the Interactive Tree Of Life (iTOL) software (http://itol.embl.de/), an online tool for the display and annotation of phylogenetic trees (Letunic et al., 2006).