Mechanism of cell-associated HIV-1 transmission

描述（由申请人提供）：人类免疫缺陷病毒1型（HIV-1）是人类艾滋病的病原体。树突状细胞（Dendritic cells，DC）是HIV-1病毒感染宿主后早期靶向的细胞类型之一，在HIV-1病毒感染和传播过程中起着重要作用。虽然DC本身总是被感染，但DC捕获的HIV-1颗粒有效地传递到CD 4 + T细胞，这是HIV-1反式感染的机制。尽管已经进行了广泛的研究，但是HIV-1颗粒侵入DC并逃避细胞内防御的机制仍然是难以捉摸的。已经提出了许多树突状细胞特异性HIV-1附着因子，以HIV-1包膜gp 120依赖性方式解释DC介导的病毒捕获。但是，靶向中和DC中的任何或所有这些先前提出的HIV-1附着因子既不能抑制病毒捕获，也不能抑制捕获的HIV-1颗粒从DC向T细胞的传播，这表明DC中存在gp 120非依赖性病毒捕获机制。我们建议，HIV-1可以结合DC使用鞘糖脂表达的病毒颗粒膜的脂质双层。该项目的主要目标之一是确定以鞘糖脂依赖性方式捕获HIV-1颗粒的受体。基于我们的初步研究结果，我们将把我们的注意力集中在DC表面表达的GPI连接蛋白。我们将在这一蛋白亚群中鉴定推定的受体，其表达在从单核细胞分化成DC时被诱导，并且其表达在DC成熟时显著增强。我们将定义GSL依赖的HIV结合到这个假定的受体后，DC内HIV-1颗粒进入的内吞区室的性质，以及随后的细胞内运输机制，该机制靶向捕获的病毒颗粒远离溶酶体降解途径。最后，我们将比较和对比病毒颗粒在获得gp 120依赖性与GSL依赖性附着因子后的命运，并确定病毒颗粒膜中存在的GSL是否对将HIV-1颗粒靶向DC介导的T细胞反式感染途径至关重要。了解这种情况发生的机制将提供有关HIV -树突状细胞相互作用途径中关键步骤的信息，并提供对树突状细胞在HIV-1发病机制中作用的见解。此外，阐明HIV-1附着于DC的这种机制可能为设计特异性靶向HIV-1生命周期早期阶段的抗病毒药物提供新的靶点。 公共卫生相关性：该项目的目的是确定树突细胞捕获人类免疫缺陷病毒1型（HIV-1）的机制，这是体内病毒感染和传播的关键步骤。详细了解以Env非依赖性、鞘糖脂依赖性方式捕获HIV-1并导致DC内HIV感染性隔离的受体是HIV-1发病机制中的关键步骤，并可能导致抗病毒药物如杀微生物剂的开发，以防止HIV-1传播给幼稚宿主。

DESCRIPTION (provided by applicant): Human immunodeficiency virus type 1 (HIV-1) is the causative agent of AIDS in humans. Dendritic cells (DCs) are one of the initial cell types that are targeted by the virus early following virus transmission to a naive host, and play a critical role in the establishment of productive virus infection and dissemination of HIV-1 in vivo. While DCs themselves are invariably infected, HIV-1 particles captured by DCs are efficiently transmitted to CD4+ T cells, a mechanism of HIV-1 trans infection. Though studied extensively, the mechanisms by which HIV-1 particles invade DCs and evade intracellular defenses have remained elusive. A number of dendritic cell-specific HIV-1 attachment factors have been proposed to account for DC-mediated virus capture in a HIV-1 envelope gp120 dependent manner. But targeted neutralization of any or all of these previously proposed HIV-1 attachment factors in DCs, fails neither to inhibit virus capture nor transmission of captured HIV-1 particles from DCs to T cells, suggesting the existence of gp120-independent virus capture mechanism(s) in DCs. We propose that HIV-1 can bind DCs using glycosphingolipids expressed in the lipid bilayer of the virus particle membrane. One of the major goals of this project is to identify the receptor that captures HIV-1 particles in a glycosphingolipid-dependent manner. Based on our preliminary findings, we will focus our attentions on GPI-linked proteins expressed on DC-surface. We will identify the putative receptor amongst this subset of proteins whose expression is induced upon differentiation from monocytes into DCs and whose expression is significantly enhanced upon maturation of DCs. We will define the nature of the endocytic compartment accessed by HIV-1 particles within DCs upon GSL-dependent HIV binding to this putative receptor and the ensuing intracellular trafficking mechanism that targets captured virus particles away from lysosomal degradation pathways. Finally, we will compare and contrast the fate of virus particles upon accessing a gp120-dependent versus GSL-dependent attachment factor(s) and determine if GSLs present in the virus particle membrane are crucial for targeting HIV-1 particles to the DC-mediated T cell trans infection pathway. Understanding the mechanism by which this occurs will provide information about a key step in the HIV - dendritic cell interaction pathway, and provide insights into the role of dendritic cells in HIV-1 pathogenesis. Furthermore, elucidation of this mechanism of HIV-1 attachment to DCs might provide novel targets for design of anti-virals that specifically target an early step in the HIV-1 life cycle. PUBLIC HEALTH RELEVANCE: The aim of this project is to identify the mechanism(s) by which human immunodeficiency virus type 1 (HIV-1) is captured by dendritic cells, a critical step in the establishment of infection and dissemination of virus in vivo. A detailed understanding of the receptor that captures HIV-1 in a Env-independent, glycosphingolipid-dependent manner, and results in sequestration of HIV infectivity within DCs is a crucial step in HIV-1 pathogenesis, and could lead to the development of anti-virals such as microbicides that prevent transmission of HIV-1 to a naive host.