The Acquirement Of Recombinant Virus-Like Particles Of PPV VP2 Gene With PCV2 ORF2 Gene And Its Partial Biological Characteristics

In this experiment, the amplified VP2 gene (PPV strain SC-1) was inserted intoeukaryotic expression vector pPI-2.EGFP, and the recombinant plasmid pPI-2.EGFP.VP2was obtained. PCV2 ORF2 gene was amplified using the recombinant plasmid pMD-PCVwhich contains the whole genome of PCV2 strain SC as template, then the gene wasinserted into pPI-2.EGFP.VP2, and the eukaryotic expression vectorpPI-2.EGFP.VP2.ORF2 containing PPV VP2 gene, PCV2 ORF2 gene and EGFP reportgene was constructed. Transfection of pPI-2.EGFP.VP2.ORF2 DNA to vero cell wasmediated by liposome, the fusion expression of green fluorescent protein was observed.Vero cells which showed obvious green fluorescent were prepared for electronmicroscopeobservation, and the VLPs formed by PPV VP2 were observed. Healthy piglets wereimmunized using pPI-2.EGFP.VP2.ORF2 DNA, the dynamic variation of blood Tlymphocytes and the antibody variation of PPV and PCV2 in serum was measured. Theresults showed that the ratio of CD₃⁺, CD₄⁺ T lymphocyte and peripheral blood lymphocyteof immunized piglets raised in a certain degree, CD₈⁺ T lymphocyte fell 7-14d afterimmunization, and then raised. Relatively high level of PPV, PCV2 specific antibody wasdetected from serum at the same time, and this indicated that after pPI-2.EGFP.VP2.ORF2transfection, the virus-like particles formed by PPV VP2 gene and PCV2 ORF2 generecombinant had good immunogenicity. The pPI-2.EGFP.VP2.ORF2 plasmid vectorconstructed in this experiment contained the unnecessary gene region gI fragment ofpseudorabies virus (PRV), which can homologously recombine with pseudorabies virus, soPRV-PPV-PCV triple genetic engineering vaccine can then be constructed.