出血性大肠杆菌O157 Eae-Stx1/2B融合蛋白的免疫学特性

为了研究重构融合蛋白Eae-Stx1/2B免疫特性及对出血性大肠杆菌感染的免疫保护作用,进行了细胞粘附抑制试验和免疫保护试验。结果证明Eae-Stx1/2B融合蛋白免疫血清在体外能降低出血性大肠杆菌对HEp-2细胞的粘附作用,这一特性在出血性大肠杆菌疫苗设计中具有重要价值。以纯化的融合蛋白Eae-Stx1/2B为抗原对小鼠进行腹腔注射免疫和滴鼻免疫,ELISA检测结果显示,2次免疫后7 d,免疫组抗Eae-Stx1/2B融合蛋白和抗出血性大肠杆菌O157血清IgG抗体显著高于未免疫组;用出血性大肠杆菌O157强毒株EDL933攻击免疫小鼠,免疫组小鼠排菌时间显著缩短,免疫组小鼠存活率均高于未免疫组,免疫组小鼠体质量恢复增长较快。上述试验结果表明,Eae-Stx1/2B融合蛋白对出血性大肠杆菌感染有保护作用。

Immunological characterization of Eae-Stx1/2B fusion protein of EHEC O157

To assess the effect of Eae-Stx1/2B on EHEC infection,adherence assays and protection against the challenges of EHEC O157 were investigated.Anti-Eae-Stx1/2B sera(or normal sera as controls) were added to EHEC bacteria suspended in adherence media,adherence decrease was microscopically observed indicating that polyclonal sera possess the capacity to block bacterial binding to HEp-2 cells.After intraperitoneal and intranasal inoculation with Eae-Stx1/2B,the titer of the serum anti-Eae-Stx1/2B and anti-EHEC IgG antibody for the immunized mice was measured by ELISA.High titer polyclonal anti-Eae-Stx1/2B sera were elicited upon intraperitoneal injection of Eae-Stx1/2B in mice.Testing of antibody titer showed that polyclonal antibodies pruducted from day 7 and reached their peak on day 21,and then decreased.After being challenged with EHEC O157:H7 EDL933,the mice,injected i.p.twice or i.n.three times with purified Eae-Stx1/2B,displayed a significant reduction in the fecal shedding of EHEC O157 versus the unimmunized mice.The survive rate in immunized mice was higher than in unimmunized mice.Weight of immunized mice recovered more quickly than that of unimmunized mice.These results suggested that immunization with Eae-Stx1/2B could induce an immune response to provide some protection against challenge with wild-type E.coli O157:H7.