Abstract: In order to construct efficient porcine reproductive and respiratory syndrome (PRRS) DNA vaccines and carrying HSP70 gene which can be used as an adjuvant enhancing immune function, we constructed the fusion expression vector PCI-ORF5-ORF6A and PCI-ORF5-ORF6B-HSP70 which comprehended PRRSV ORF5 and ORF6 genes. The two kinds of fusion expression vectors were transfected Cos-7 cells. IFA results showed that the two fusion expression vector in Cos-7 cells could express and western blot test confirmed that the specific bands about 42.7 Ku and 112.2 Ku could be found from transfection of plasmid pCI-ORF5-ORF6A and pCI-ORF5-ORF6B-Hsp70. It showed that the recombinant plasmid in Cos-7 cells were efficiently transcribed and expressed, and the expression of the protein was immunogenic．

Key words: PRRSV, Hsp70, Cos-7 cell