Fusion expression of SLT-IIeB gene and FedF gene of Ee in Escherichia coli and its immunogenicity
大肠杆菌Ee株SLT-IIeB与FedF基因的融合表达及表达产物的免疫原性研究

The DNA fragment encoding the truncated SLT-IIeB and FedF of Ee strain were fused to the downstream of glutathione S-transferase (GST) of pGEX-KG expression vector, resulting in the fusion expression plasmid pKSF. After transformed into E. coli BL21 (DE3) and induced by IPTG, the results of SDS-PAGE showed that the GST-SF fusion protein was expressed in high level. Western blot was performed to confirm that the expressed fusion protein could specifically react with mouse anti-SLT-IIeB antiserum, mouse anti-FedF antiserum and moue anti-GST monoclonal antibody respectively. The fusion protein was further purified and used as an antigen for preparation of immune serum. The anti-sera of GST-SF were able to restrain the toxicity of SLT-IIe to Vero-E6 cells and inhibit the adhesin of F18 fimbriae to brush borders of swine in vitro. Groups of SPF KM mice were vaccinated subcutaneously at 0 week with 25 micrograms and at 2 weeks with 25 micrograms of purified GST-SF, GST-B, GST-F and challenged intraperitoneally with volume of 5 LD50 Ee strain. The results show the fusion protein GST-SF had more shrong immunogenicity and better protection against Ee strain.