Construction and immunogenicity of recombinant adenovirus expressing the capsid protein of porcine circovirus 2 (PCV2) in mice

Porcine circovirus 2 (PCV2) has been implicated as the etiological agent of some diseases, mainly postweaning multisystemic wasting syndrome (PMWS) and porcine dermatitis and nephropathy syndrome (PDNS). The capsid (Cap) protein encoded by the PCV2 ORF2 gene may be an excellent candidate for vaccination. In this study, the Cap protein gene was amplified by PCR, and cloned into the transfer vector pShuttle-CMV. After co-transformation of PmeI-linearized recombinant plasmid pShuttle-CMV-ORF2 and the bone vector pAdEasy-1 into Escherichia coli bacteria strain BJ5183, recombinant plasmid containing Cap protein gene (pAd-ORF2) was obtained and identified with PCR. Upon transfection of PacI-linearized plasmid pAd-ORF2 in 293 cell line, a recombinant adenovirus was obtained and named as rAd-Cap with viral titer of 1013.0 TCID50/ml. The expression of the Cap protein in the 293 cells infected with rAd-Cap was confirmed with specific antibody to PCV2 by Western blotting and IPMA. Mice were inoculated with 108, 1010 and 1012 TCID50/mouse of rAd-Cap and boosted 2 weeks later, and they could generate antibody against PCV2 detected by indirect ELISA, Western blot and neutralizing activity assay. It indicated that the rAd-Cap was able to express the capsid of PCV2 and could elicit immune responses against the PCV2 in mice. The recombinant adenovirus might be an attractive candidate vaccine for preventing the disease associated with PCV2 infection.