Expression of porcine circovirus type 2 recombinant capsid protein using insect baculovirus

Porcine circovirus type 2(PCV2) genome contains two major open reading frames(ORFs),ORF1 encoding the viral replication-associated protein(Rep) and ORF2 encoding the viral capsid protein(Cap).To express the Cap protein in insect cells,PCV2-ORF2 gene was amplified by PCR and inserted into a baculovirus transfer plasmid vector.The recombinant plasmid was confirmed using restriction enzymes analysis and DNA sequencing.The insect cells(Sf-21) were transfected with a mixture of linearized baculovirus DNA and the recombinant plasmid.A titre of 1.28×10~8 pfu/ml recombinant baculovirus expressing the Cap protein was obtained latter after three circles of plaque cloning.The recombinant fusion capsid protein with a molecular weight of 32.8?kμ was shown to account for 17.2?% of the total protein in SDS-PAGE.The immuno-reactivity of the protein was confirmed by Western-blotting using antisera against PCV2.The results suggest that the recombinant capsid protein may be used for studies on molecular diagnosis,subunit vaccine and molecular biology for PCV2.