ACTIVITY OF MENINGOCOCCAL VACCINE CANDIDATE GNA1870

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目及 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 脑膜炎奈瑟菌结合因子H（fH），这是补体旁路途径的关键调节因子。一种29 kD的fH结合蛋白 在脑膜炎球菌外膜中表达的脂蛋白通过质谱鉴定为GNA 1870，GNA 1870是一种目前正在评估的作为广谱脑膜炎球菌候选疫苗的脂蛋白。通过以下方式确认GNA 1870为完整细菌上的fH配体：1）在缺失GNA 1870后消除fH结合，和2）通过抗GNA 1870 mAb阻断fH结合。fH结合全细菌和纯化的rGNA 1870，代表三种变体GNA 1870家族中的每一种。我们发现fH结合的量与细菌GNA 1870表达的水平相关。在原本是低水平GNA 1870表达者（并且通过流式细胞术结合低量fH）的菌株中，高水平的变体1GNA 1870表达（通过gna 1870的等位基因置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结合GNA 1870缺失突变体的减少伴随着C3结合的增强和突变体杀伤的增加。相反，高水平的GNA 1870表达和fH结合增强血清抵抗力。我们的研究结果支持这一假设，即抑制补体下调蛋白的结合奈瑟球菌表面的特异性抗体可能会增强内在的杀菌活性的抗体，导致两种不同的机制抗体介导的疫苗的效力。这些数据为脑膜炎球菌疫苗中包含该分子提供了进一步的支持。为了反映这种分子的关键功能，我们建议将其称为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.