Abstract: To express ORF3 gene of porcine circovirus 2（PCV-2） in E.coli, analyze the antigenicity of ORF3 protein, according to the amino acid sequence of PCV-2 strain in GenBank, a pair of specific primer was designed to amplify the fragment encoding ORF3 gene. This fragment was cloned into the multiple cloning sites of pET-32a (+) vector. The recombinant plasmid was designated pET32a-ORF3 and was transformed into E.coli Rosetta-blue (DE3) pLacⅠ competent cells. Expression of recombinant protein was induced by addition of final concentration of 1.0 mmol/L IPTG under 37 ℃ condition. The length of PCR product of interest was 315 base pairs. The size of recombinant amino acid was 29 ku. The results of western blotting showed that it could be recognized by anti-His tagged mouse monoclonal antibody and could not be recognized by swine serum infected with PCV-2. The results showed that ORF3 of PCV-2 was expressed successfully in E.coli and the ORF3 protein didn’t exhibit reaction genicity. These results were benefit to research for function and characteristics of ORF3 of PCV-2.

Key words: porcine circovirus 2（PCV-2）; ORF3 gene; prokaryotic expression