Expression of GP5-M Fusion Protein of Porcine Reproductive and Respiratory Syndrone Virus(PRRSV) and Establishment of ELISA Diagnose Based on the Recombinant Fusion Protein
猪繁殖与呼吸综合征病毒(PRRSV)GP5-M在大肠杆菌中的融合表达及其ELISA诊断方法的建立

The cDNA fragment encoding the truncated GP5 and the full-length M pr o tein of Porcine Reproductive and Respiratory Syndrone Virus(PRRSV)were orderly fused to the downstream of glutathione S-transferase(GST) of pGEX-KG expressi on vector, resulting in the fusion expression plasmid pKG-56. After transformed in to E.coli BL21(DE3)and induced by IPTG, the results of SDS-PAGE showed t hat t he GST-GP5-M fusion protein was expressed in high level. Western-blot was per for med to confirm that the expressed fusion protein could specifically react with a ntiserum against PRRSV. The fusion protein was further purified and used as an a ntigen to establish a novel PRRSV ELISA diagnose assay(P56-ELISA). Comparison between P56-ELISA and the abroad kit IDEXX-ELISA showed the two methods had 94 .1 percent agreement by detecting 205 serum samples, indicating that the indirect P56-ELISA was specific and sensitive. The correlation between virus neutralization antibody of the infected pigs (not convalescent pigs) and a ntibody response to the fusion protein GP5-M was further studied.The regressio n function analysis suggested that there was no significant correlation between E LISA antibody response (OD 630nm) to the fusion protein GP5-M in cli nical serum and their specific neutralizing titers.