ACTIVITY OF MENINGOCOCCAL VACCINE CANDIDATE GNA1870

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 脑膜炎奈瑟菌结合因子H(Fh)，这是替代补体途径的关键调节因子。脑膜炎球菌外膜表达的29kD FH结合蛋白经质谱仪鉴定为GNA1870，这是一种目前正在评估的广谱脑膜炎球菌候选疫苗的脂蛋白。通过1)删除GNA1870后取消Fh结合，以及2)用抗GNA1870单抗阻断Fh结合，确认GNA1870是完整细菌上的Fh配体。FH与整个细菌结合，纯化的rGNA1870代表三个变异的GNA1870家族中的每一个。我们发现FH结合量与细菌GNA1870的表达水平相关。在原本是低水平GNA1870表达的菌株中，高水平的变异体1 GNA1870的表达(通过GNA1870的等位基因替换或通过质粒驱动的高水平表达)恢复了高水平的FH结合。FH与GNA1870缺失突变体结合的减弱伴随着C3结合的增强和突变体的杀伤增加。相反，高水平的GNA1870表达和FH结合增强了血清抵抗力。我们的发现支持这样一种假设，即通过特定的抗体抑制补体下调调节蛋白与新表面的结合可能会增强抗体的内在杀菌活性，从而导致抗体介导的疫苗效力的两种不同机制。这些数据进一步支持将该分子纳入脑膜炎双球菌疫苗。为了反映该分子的关键功能，我们建议将其命名为FH结合蛋白。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Neisseria meningitidis binds factor H (fH), a key regulator of the alternative complement pathway. A 29 kD fH-binding protein expressed in the meningococcal outer membrane was identified by mass spectrometry as GNA1870, a lipoprotein currently under evaluation as a broad-spectrum meningococcal vaccine candidate. GNA1870 was confirmed as the fH ligand on intact bacteria by 1) abrogation of fH binding upon deleting GNA1870, and 2) blocking fH binding by anti-GNA1870 mAbs. fH bound to whole bacteria and purified rGNA1870 representing each of the three variant GNA1870 families. We showed that the amount of fH binding correlated with the level of bacterial GNA1870 expression. High levels of variant 1 GNA1870 expression (either by allelic replacement of gna1870 or by plasmid-driven high-level expression) in strains that otherwise were low-level GNA1870 expressers (and bound low amounts of fH by flow cytometry) restored high levels of fH binding. Diminished fH binding to the GNA1870 deletion mutants was accompanied by enhanced C3 binding and increased killing of the mutants. Conversely, high levels of GNA1870 expression and fH binding enhanced serum resistance. Our findings support the hypothesis that inhibiting the binding of a complement down-regulator protein to the neisserial surface by specific Ab may enhance intrinsic bactericidal activity of the Ab, resulting in two distinct mechanisms of Ab-mediated vaccine efficacy. These data provide further support for inclusion of this molecule in a meningococcal vaccine. To reflect the critical function of this molecule, we suggest calling it fH-binding protein.