Genetic Susceptibility of Antibody-dependent Enhancement of Flaviviruses

项目概要： 抗体依赖性增强（ADE）是一些黄病毒感染的特征性现象， 已知在人类的四种DENV血清型之间发生，但也可能在连续的DENV之间发生， 然后是ZIKV感染（反之亦然）。ADE发生时，亚中和水平的抗体对一个 黄病毒感染交叉反应以增强密切相关的黄病毒感染。ADE完全依赖于 IgG抗体与易感细胞（如单核细胞/巨噬细胞）上发现的Fc受体的结合。在 在人类中，Fc ε RIIA基因（rs 1801274）中存在非同义多态性，导致 位置131处的精氨酸（Arg）至组氨酸（His）的变化，其已显示改变了这种结合的亲和力。 IgG抗体的受体。我们假设，编码高表达的Fc ε RIIA的纯合子个体， 与低亲和力His等位基因纯合的个体相比， 亲和力Arg等位基因。在本申请中，我们将使用Arg 131纯合的K562细胞或 His 131等位基因以及基于基因型分层的原代人单核细胞，以测试该SNP如何影响 体外黄病毒的ADE（目的1）。使用我们发现的两种黄病毒特异性单克隆抗体克隆， 增强K562细胞中的黄病毒感染，我们将产生IgG亚类转换变体（IgG 1、IgG 2、IgG 3或IgG 4）。 IgG 4），以确定每个IgG亚类在介导黄病毒ADE中的相对贡献（目的2）。

PROJECT SUMMARY: Antibody-dependent enhancement (ADE) is a phenomenon characteristic of some flavivirus infections and best known to occur between the four DENV serotypes in humans, but may also occur between sequential DENV, then ZIKV infections (or vice versa). ADE occurs when subneutralizing levels of antibodies raised against one flavivirus infection cross-react to enhance a closely related flavivirus infection. ADE is entirely dependent on the binding of IgG antibodies to FcRs found on susceptible cells, such as monocytes/macrophages. In humans, there is a nonsynonymous polymorphism that occurs in the FcRIIA gene (rs1801274) that leads to an arginine (Arg) to histadine (His) change at position 131 that has been shown to alter the affinity of this receptor for IgG antibodies. We hypothesize that individuals homozygous for the FcRIIA encoding for the high affinity His allele are at higher risk for developing ADE of flaviviruses than individuals homozygous for the low affinity Arg allele. In this application, we will test this using K562 cells homozygous for the Arg131 or the His131 allele as well as primary human monocytes stratified based on genotype to test how this SNP impacts ADE of flaviviruses in vitro (Aim 1). Using two flavivirus-specific monoclonal antibody clones that we found to enhance flavivirus infection in K562 cells, we will generate IgG subclass switch variants (IgG1, IgG2, IgG3, or IgG4) to determine the relative contribution of each IgG subclass in mediating ADE of flaviviruses (Aim 2).