Regulation of B cell responses to West Nile Virus Infections

这项提议的一个主要目标是阐明先天免疫传感机制的过程， 编程B谱系细胞以产生保护性抗西尼罗病毒（WNV）IgM和IgG抗体。体液 对西尼罗河病毒的免疫是必要的，也足以保护宿主免受疾病的侵害，然而， 协调对西尼罗河病毒的初始先天性和随后的适应性抗体（Ab）应答的免疫调节系统 明白我们将阐明树突状细胞（DC）和B细胞如何对西尼罗河病毒作出反应，以及IgM和B细胞如何迅速地对西尼罗河病毒产生反应。 IgG抗西尼罗河病毒中和抗体产生。我们假设DC亚群的初始先天编程 决定了对西尼罗河病毒的保护性抗体应答的质量和持续时间。为了研究这个假设 我们将进行以下具体目标：目标1：我们将比较致病性西尼罗河病毒得克萨斯州的过程， （WN-TX）和减毒的WNV马达加斯加（WN-MAD）株。我们建议 高致病性和低致病性WNV在它们如何感染、改变和编程DC方面不同。我们将量化变化 感染后早期DC亚群数量、存活率、细胞因子产生和感染。项目1，我们 将确定哪些先天免疫因子调节初始DC反应和对西尼罗河病毒感染的易感性 通过比较野生型（WT）小鼠与C3和IPS-1 KO小鼠中的DC应答和感染， 骨髓（BM）嵌合体，其中DC已被消融，我们将确定如何DC消融或 DC中IPS-1、TLR-3或其它先天免疫因子的缺乏影响WNV感染后的早期事件。 目的2：确定快速IgM中和的分子和细胞要求 对西尼罗河病毒的抗体反应。确定边缘区（MZ）B细胞在保护性IgM免疫中的作用 我们将评估IgM应答和MZ B细胞缺陷型CD22 KO和Notch2 fl/fl 条件性KO小鼠。DC在对包裹的细菌的快速IgM应答中起关键作用;使用混合的 我们将确定DC的消融或DC中DC的缺失如何影响骨髓嵌合体中DC的表达。 IPS-1、BAFF或其他先天性免疫因子影响中和IgM Ab应答的发展。目的 3：我们将研究免疫IgM是否需要MZ B细胞来促进保护性IgG免疫。递送 Ag与MZ相关DC的结合可导致强烈的IgG抗体应答。我们将检查是否交付西尼罗河病毒 E蛋白对MZ DCs的作用可以诱导IgM和IgG中和Ab反应，如果是这样，这种形式的Ag是否 递送可用于诱导对西尼罗河病毒的保护性、杀菌性免疫。这些研究将带来新的 深入了解如何最好地设计针对西尼罗河病毒和其他黄病毒的疫苗。

A major goal of this proposal is to elucidate processes by which innate immune sensing mechanisms program B lineage cells to produce protective anti-West Nile virus (WNV) IgM and IgG antibodies. Humoral immunity to WNV is both necessary and sufficient to protect hosts from disease, however, the early events that coordinate the initial innate and subsequence adaptive antibody (Ab) responses to WNV are not well understood. We will elucidate how dendritic cells (DCs) and B cells respond to WNV and how rapid IgM and IgG anti-WNV neutralizing Abs develop. We hypothesize that initial innate programming of DC subsets dictate both the quality and the duration of protective Ab responses to WNV. To investigate this hypothesis we will conduct the following Specific Aims: Aim 1: We will compare the course of pathogenic WNV Texas (WN-TX) and attenuated WNV Madagascar (WN-MAD) strains early after in vivo infection. We propose that high and low pathogenic WNVs differ in how they infect, alter and program DCs. We will quantify changes early after infection in DC subset numbers, survival, cytokine production and infection. With Project 1, we will determine what innate immune factors regulate initial DC responses and susceptibility to WNV infection by comparing DC responses and infection in wildtype (WT) mice vs. C3 and IPS-1 KO mice Using mixed bone marrow (BM) chimeras, in which DCs have been ablated, we will determine how DC ablation or the absence in DCs of IPS-1, TLR-3 or other innate immune factors affects early events after WNV infection. Aim 2: To determine the molecular and cellular requirements for the development of rapid IgM neutralizing antibody responses to WNV. To determine the role of marginal zone (MZ) B cells in protective IgM immunity to WNV, we will assess IgM responses and susceptibility of MZ B cell-deficient CD22 KO and Notch2fl/fl conditional KO mice. DCs play a pivotal role in rapid IgM responses to encapsulated bacteria; using mixed BM chimeras, in which DCs have been ablated, we will determine how DC ablation or the absence in DCs of IPS-1, BAFF or other innate immune factors affects the development of neutralizing IgM Ab responses. Aim 3: We will investigate if MZ B cells are required for immune IgM to promote protective IgG immunity. Delivery of Ag to MZ-associated DCs can lead to a strong IgG antibody response. We will examine if delivery of WNV E protein to MZ DCs can induce IgM and IgG neutralizing Ab responses, and if so whether this form of Ag delivery can be used to induce protective, sterilizing immunity to WNV. These studies will lead to new insights into how best to design vaccines to WNV and other flaviviruses.