Abstract: 【Objective】To investigate the immune efficiency of the suicidal DNA vaccines of porcine reproductive and respiratory syndrome virus (PRRSV). 【Method】The ORF5 and ORF6 genes were subcloned into the downstream of two independent subgenomic promoter 26S of a suicidal DNA vaccine expression vector pCSA2 resulting in the plasmid pSFV-56 co-expressing GP5 and M proteins.【Result】The result of Western blot showed that the GP5 and M proteins were expressed and formed disulfided-linked heterodimer. The suicidal DNA vaccine pSFV-56 was injected Balb/c mice and piglets to evaluate the induced immunological responses in vivo. The specific detectable anti-PRRSV neutralizing antibodies were produced in the vaccinated mice at 4 weeks post primary vaccination (PPV) and reached a peak 1:32 at 8 weeks PPV. The specific stronger cell-immunity responses were also observed. In addition, it was observed that the 1:8-1:16 neutralizing antibodies of the vaccinated piglets and the specific cell-immunity responses were produced.【Conclusion】The results of the present study indicated that the suicidal DNA vaccine pSFV-56 has well immunity and the capability inducing higher immune responses in the animals.

Key words: “Suicidal” DNA vaccine, porcine reproductive and respiratory syndrome virus (PRRSV), co-expressing GP5 and M