A candidate DNA vaccine encoding a fusion protein of porcine complement C3d-P28 and ORF2 of porcine circovirus type 2 induces cross-protective immunity against PCV2b and PCV2d in pigs

Abstract

Abstract Background Porcine circovirus type 2 (PCV2) is an economically important viral pathogen for swine industry worldwide. However, current PCV2 vaccines provide incomplete protection against the PCV2d, which has recently emerged as the predominant pathogenic form of PCV2. Methods To develop a novel DNA vaccine with high efficacy against PCV2d virus, we fused the ORF2 of PCV2d to three copies of the minimum-binding domain of the complement C3 cascade terminal component, C3d-P28. Expression of ORF2 alone (pVO) or fused C3d-P28 (pVOC3) were verified by immunofluorescent assay. Vaccine efficacy was tested by measured the DNA copy and T and B cell immune response. Results Vaccination with pVOC3 reduced the levels of PCV2 genomic DNA after pigs were infected with either PCV2b or PCV2d genotypes, produced potent antibodies against PCV2, and stimulated PCV2-specific interferon-γ secreting cells. Conclusion Results suggested pVOC3 would be a safe and effective DNA vaccine to confer cross-protection against both PCV2b and PCV2d genotypes in pigs.

Keywords

• DNA vaccine
• C3d-P28
• ORF2
• PCV2b, PCV2d