With respect to pCAV, which is a pcDNA3.1 plasmid carrying the entire CAV genome, the VP1 protein also displayed its DNA binding activity in terms of altered DNA migration pattern, as illustrated in Fig. 2b. In other words, regardless of whether the plasmid DNA used in the protein-DNA binding reaction was from pcDNA3.1 or pCAV, there was no significant effect on the resulting pattern of DNA migration (Fig. 2b, c and d). However, it is worth noting that the DNA migration of the circular dsDNA plasmid in the agarose gel displayed open circular dsDNA (form I, with a higher molecular weight pattern) and supercoiled dsDNA (form II, with a lower molecular weight pattern), simultaneously (Fig. 2b). The VP1 protein was bound to supercoiled dsDNA. which demonstrated that DNA shifting was more obvious than open circular dsDNA.