Abstract: This study was to develop ORF2 DNA vaccine against PCV2 and evaluate its immunity effect and safety.Method A pair of specific primers was synthesized to amplify the PCV2-ORF2 by PCR.PCV2-ORF2 was cloned into T vector and named T-ORF2.T-ORF2 and PcDNA3.1 were double digested under same conditions,connected by using T4 DNA ligase,and cloned.The positive recombinant plasmids(DNA vaccine) were confirmed by double digestion and named PcDNA3.1-ORF2.The DNA vaccine was transfected in Vero cells with lipofectamine 2000 for RT-PCR analysis.At the same time,100 μg of the vaccine was intramuscular injected into Balb/c mice at two-week intervals.On the 14th and 28th day after the first vaccination,serums were collected for ELISA test.On the 56th day,the genomes of parenchymal organ including heart,liver,spleen,lung and kidney of the vaccinated mice were extracted for PCR amplification to determine safety of the DNA vaccine.Result The results indicated that the DNA vaccine was successfully made,PCV2-ORF2 gene was expressed in Vero cells in vitro,and the vaccine did induce immune response in mice.The safety test showed that ORF2 genes could not be integrated into the mice chromosome.Conclusion The resultant DNA vaccine successfully induced immune response in mice and was confirmed to be safe.