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[Construction of infectious DNA clone of chimeric porcine circovirus type 1-2 and its immunogenicity in mice].

OBJECTIVE
To construct infectious DNA clone of chimeric porcine circovirus type 1-2.


METHODS
Recombinant plasmid pSK-PCV1 delta ORF2-PCV2-ORF2 (pSK-sPCV1-2) was constructed by replacing the PCV1 capsid gene with that of PCV2 in the backbone recombinant containing the complete genomic DNA of PCV1. The full-length chimeric fragment PCV1-2 was excised from pSK-sPCV1-2 and cloned into the same recombinant to form the dimerized tandem DNA clone pSK-dPCV1-2.


RESULTS
The sequence of PCV1-2 infectious clone was confirmed by sequencing. PCV1-2 virus was observed to be infectious after transfecting into both PK-15 and Dulac cells. BALB/c mice were immunized with recombinant virus PCV1-2 and sera samples collected from all control and vaccinated animals at -1, 7, 14, 21, 28, 35, 42 day post-inoculation (dpi) were assayed for anti-PCV2 capsid antibodies by ELISA. The results indicated that the chimeric PCV1-2 virus with the immunogenic ORF2 capsid gene of pathogenic PCV2 cloned into the nonpathogenic PCV1 genomic backbone induced specific antibodies against the pathogenic PCV2 capsid antigen in almost all mice at 42 dpi.


CONCLUSION
PCV1-2 infectious clone was constructed, and the recombinant virus strain of PCV1-2 was of some immunogenicity.