B群脑膜炎球菌重组H因子结合蛋白的免疫原性研究

Immunogenicity study on recombinant fHBP of meningococcal group B

目的:通过检测血清抗体滴度和杀菌抗体检测(SBA)评价重组H因子结合蛋白(factor H binding protein,fHBP)的免疫原性。方法:选择并合成fHBP序列,连接至pET43.1a质粒,转化大肠杆菌BL21(DE3),表达两个亚家族的重组fHBP蛋白,fHBPA和fHBPB,经过纯化后免疫家兔和小鼠,通过ELISA和SBA试验检测免疫抗血清效价和B群脑膜炎球菌流行菌株的杀菌滴度。结果:fHBP免疫兔血清效价均大于2.0×10^(6),免疫小鼠血清效价高于1.0×10^(6)。69株流行株SBA试验中fHBP免疫兔血清对41株A亚家族和20株B亚家族均有大于1∶128杀菌滴度,亚家族靶菌之间没有交叉保护作用。fHBPA小鼠血清对A亚家族流行株Nm210902、Nm211009、Nm450522平均滴度为1∶1024、1∶608、1∶861,对Nm510703、Nm311304、Nm431002流行株的滴度为1∶234、1∶861、1∶430;fHBPB小鼠血清对B亚家族流行株Nm311302、Nm311113和Nm321114的杀菌滴度分别是1∶2896、1∶1878和1∶430。而fHBPA和fHBPB混合蛋白质免疫鼠血清Nm210902、Nm510703和Nm311302平均滴度分别1∶876、1∶274、1∶1858,对3株靶菌均存在有效杀菌。结论:fHBP免疫抗血清效价均在1.0×10^(6)水平以上,对61株B群流行株的杀菌滴度大于1∶128,对69株B群脑膜炎球菌流行株有94.2%的保护效果。

Objective To evaluate the immunogenicity of recombinant factor H binding protein(fHBP)by detecting serum antibody titer and serum bactericidal antibody test(SBA).Methods fHBP sequence was selected and synthesized,connected to plasmid pET43.1a,transformed to Escherichia coli BL21(DE3),and expressed two recombinant fHBP proteins,included two subfamilies,fHBPA and fHBPB.After purification,the recombinant fHBP proteins were immunized to rabbits and mice.The immune antiserum titer and the bactericidal titer to epidemic strains of meningococcal bacteria group B were measured by ELISA and SBA respectively.Results The antiserum titer of fHBP immunized rabbits was greater than 2.0×10^(6),and that of immunized mice was not less than 1.0×10^(6).fHBP immunized rabbit serum had bactericidal titer more than 1∶128 to 41 strains A subfamily and 20 strains B subfamily in the SBA against 69 endemic strains,and there was no cross-protection between the subfamily bacteria.The bactericidal titers of mouse serum immunized fHBPA to strains A subfamily such as Nm210902 Nm211009、Nm450522 were 1∶1024,1∶608、1∶861,to Nm510703、Nm311304、Nm431002 were 1∶234、1∶861、1∶430 respectively,and mouse serum immunized fHBP B to strains B subfamily Nm311302、Nm311304、Nm431002 were 1∶876、1∶274、1∶1858,all of three strains were positive in bactericidal titers.Conclusions the titer of fHBP antiserum was higher than 1.0×10^(6),the bactericidal titer was no less than 1∶128 to 61 epidemic strains,and it has a 94.2%protective effect on 69 meningococcal epidemic strains group B.