Regulation of antibody diversification and production in HIV-1 infection

这项提议的目的是阐明HIV-1逃避的机制 体液免疫。抗体反应，包括类别转换DNA重组 (CSR)和体细胞超突变(SHM)是阻止HIV-1入侵和传播的关键。 CSR用Ig G或Ig A代替Ig M，从而赋予抗体新的效应剂 增强系统和粘膜进入部位病毒清除的功能。SHM 引入编码抗原结合可变区的基因的点突变 抗体，从而为病毒抗原的选择提供结构相关性 高亲和力的免疫球蛋白和免疫球蛋白A突变体。CSR和SHM需要激活诱导的胞苷 脱氨酶(AID)，一种由B细胞表达的生发中心(GC)酶 次级淋巴器官。这种特殊的微环境由CD4+T细胞组成 通过CD154和IL-4激活B细胞。最终，GC B细胞分化为 浆细胞，分泌大量的免疫球蛋白和免疫球蛋白A抗体。HIV-1病毒损害 对病毒抗原、机会性病原体的系统和粘膜免疫球蛋白和免疫球蛋白A反应 和疫苗通过仍然鲜为人知的机制。虽然进步 失去CD4+T细胞当然很重要，B细胞固有的异常，包括差 B细胞对CD154的反应性也参与其中。在这份提案中，我们认为 HIV-1蛋白Nef在B细胞固有缺陷的发生中起作用 HIV-1感染。我们认为，Nef也减弱了CD154依赖的CSR、SHM 作为病毒特异性的免疫球蛋白和免疫球蛋白A在全身和粘膜GC产生。我们也 假设Nef通过长距离隧道传输来靶向B细胞 从HIV-1感染细胞发出的纳米管。最后，我们提出了多重NEF 结构域在抑制B细胞CD154和IL-4信号通路中的作用 细胞。提出了三个具体目标。目标1是确定Nef-充分的能力 和Nef缺陷的HIV-1以减弱CSR、SHM和抗原特异性的Ig G和Ig A 在系统和粘膜B细胞中产生。目标二是评估长寿的能力 距离隧穿纳米管穿梭膜结合型和囊泡型Nef 从受感染的细胞到B细胞。目标3是阐明涉及到的分子相互作用 NEF介导的B细胞CD154和IL-4信号的抑制调查结果来自 这些研究应该有助于更好地理解艾滋病毒-1 逃避抗体反应。此外，拟议的研究可能会有助于 针对HIV-1的新型治疗和疫苗策略的开发。HIV-1严重损害对病毒蛋白、机会性因子和 疫苗。越来越多的证据表明，这种抗体缺陷不仅仅是由于丢失 CD4+T细胞，也受B细胞固有缺陷的影响。这个应用程序的目标是阐明 HIV-1导致B细胞功能障碍的机制。最终，得出的结果是 来自拟议的研究应该有助于开发更有效的艾滋病毒-1疫苗。

The goal of this proposal is to elucidate the mechanisms by which HIV-1 evades humoral immunity. Antibody responses, including class switch DNA recombination (CSR) and somatic hypermutation (SHM), are essential to block HIV-1 entry and spread. CSR substitutes IgM with IgG or IgA, thereby endowing antibodies with novel effector functions that enhance viral clearance systemically and at mucosal sites of entry. SHM introduces point mutations in genes encoding the antigen-binding variable region of antibodies, thereby providing the structural correlate for selection by viral antigens of higher affinity IgG and IgA mutants. CSR and SHM require activation-induced cytidine deaminase (AID), an enzyme expressed by B cells in the germinal center (GC) of secondary lymphoid organs. This specialized microenvironment comprises CD4+ T cells that activate B cells through CD154 and IL-4. Ultimately, GC B cells differentiate into plasma cells, which secrete large amounts of IgG and IgA antibodies. HIV-1 impairs systemic and mucosal IgG and IgA responses to viral antigens, opportunistic pathogens and vaccines through mechanisms that remain poorly understood. Although progressive loss of CD4+ T cells is certainly important, B cell-intrinsic abnormalities, including poor responsiveness of B cells to CD154, are also involved. In this proposal, we argue that the HIV-1 protein Nef contributes to the genesis of B cell-intrinsic defects arising during HIV-1 infection. We contend that Nef attenuates CD154-dependent CSR, SHM as well as virus-specific IgG and IgA production in systemic and mucosal GCs. We also hypothesize that Nef targets B cells by traveling through long-range tunneling nanotubules emanating from HIV-1-infected cells. Finally, we propose that multiple Nef domains contribute to the inhibition of kinases transducing CD154 and IL-4 signaling in B cells. Three specific aims are proposed. Aim 1 is to determine the ability of Nef-sufficient and Nef-deficient HIV-1 to attenuate CSR, SHM and antigen-specific IgG and IgA production in systemic and mucosal B cells. Aim 2 is to assess the ability of long- distance tunneling nanotubules to shuttle membrane-bound and vesicle-associated Nef from infected cells to B cells. Aim 3 is to elucidate the molecular interactions involved in Nef-mediated inhibition of CD154 and IL-4 signaling in B cells. Findings resulting from these studies should lead to a better understanding of the mechanisms whereby HIV-1 evades the antibody response. In addition, the proposed studies might facilitate the development of novel therapeutic and vaccine strategies against HIV-1. HIV-1 profoundly impairs antibody responses against viral proteins, opportunistic agents and vaccines. Growing evidence indicates that this antibody deficiency is caused not only by loss of CD4+ T cells, but also by B cell-intrinsic defects. The goal of this application is to elucidate the mechanisms by which HIV-1 causes B cell dysfunctions. Ultimately, findings deriving from the proposed studies should help develop more effective vaccines against HIV-1.