Host Cell Factors and AIDS Pathogenesis

宿主细胞因素与艾滋病发病机制

• 批准号: 8320329
• 负责人: GHALIB ABBAS ALKHATIB
• 金额: $ 58.87万
• 依托单位: SOUTHERN RESEARCH INSTITUTE
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-05-15 至 2014-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8320329
• 关键词: Acquired Immunodeficiency Syndrome; Apoptosis; Biological; Biological Process; Bypass; C-terminal; CCR5 gene; CD4 Positive T Lymphocytes; CXCR4 gene; Cells; Characteristics; Chronic; Disease; Drug Design; Excision; Future; Glycoproteins; Goals; HIV; HIV Envelope Protein gp120; HIV Infections; HIV-1; Health; Heterodimerization; Homosexuals; Individual; Induction of Apoptosis; Infection; Knowledge; Mediating; Molecular; Mutation; Nature; Pathogenesis; Patients; Pattern Recognition; Peptides; Peripheral Blood Mononuclear Cell; Phenotype; Physiologic pulse; Play; Production; Promoter Regions; Protein Deficiency; Proteins; Public Health; Reagent; Recombinants; Research; Resistance; Role; Sampling; Signal Pathway; Surface; Tail; Translations; Viral; Viral Load result; Virus; base; env Glycoproteins; in vivo; insight; neutralizing antibody; novel; protective effect; protein expression; receptor; research study; resistance mechanism; therapeutic target; transmission process; vaccine development; virology

DESCRIPTION (provided by applicant): A lack of CCR5 expression is associated with resistance to HIV-1 infection. This deficiency is due to homozygosity of a 32bp deletion in the CCR5 gene (CCR5 32). Several CCR5 32 individuals lacking CCR5 expression (CCR5-/-) yet HIV-1-seropositive have been identified. How the virus overcomes the CCR5 32 protective effects have not been delineated and we have investigated this in six HIV+ CCR5-/- patients. We demonstrated that peripheral blood mononuclear cells (PBMCs) isolated from exposed/uninfected (EU) CCR5- /- individuals express a truncated CCR5 32 protein. In contrast, four exposed/infected (EI) CCR5-/- patients lack expression of the CCR5 32 protein and two others expressed low levels. Pulse-chase experiments demonstrated instability of the protein in three HIV+CCR5-/- individuals. Another two had a mutation in the promoter region that was associated with low translation of the CCR5 32 protein. The lack or low CCR5 32 protein expression was associated with increased surface CXCR4. However, our results indicate that the loss of resistance in the HIV+CCR5-/- patients cannot be solely due to their increased CXCR4 levels. Expression of recombinant CCR5 32 protein restored the protective effect in three HIV+ CCR5-/- PBMC samples but failed to restore the protective effect in samples from another three HIV+ CCR5-/- individuals. Two potential mechanisms are proposed to be investigated for the loss of CCR5 32 expression in HIV+CCR5-/- subject; 1) a trans effect caused by the infecting virus or 2) a cis host effect that ultimately resulted in the creation of new signaling pathways and the loss of the resistance phenotype. We found that envelope glycoproteins (Envs) cloned from two independent CCR5-/- patients showed expanded coreceptor usage. We hypothesize that the primary HIV-1 strains isolated from the HIV+CCR5-/- individuals have unique structural determinants that allowed them to bypass the protective effect of the CCR5 32 mutation. Rapid CD4+ T cell loss despite mild viral load is characteristic of the chronic infection of these HIV+CCR5-/- patients. The novelty of our approach lay in the unique nature of these primary isolates to infect and replicate in CCR5-/- cells in vivo. The overall goal of this proposal is to define the molecular basis for the loss of the CCR5 32 protective effect. To do this we will characterize primary HIV-1 isolates from CCR5-/- patients, evaluating Env fusogenicity, apoptosis induction ability, coreceptor recognition patterns, and we will determine the role of the novel 31 residues at the C-terminus of CCR5 32 protein. PUBLIC HEALTH RELEVANCE: This application proposes to investigate the kind of HIV viruses harbored in infected homosexual individuals. Since HIV is the virus that causes acquired immunodeficiency syndrome (AIDS), the basic knowledge of these HIV viruses will provide an important new insight into AIDS pathogenesis. This project is very relevant to public health since the results of the proposed research will provide new mechanistic approaches to the design of drugs that block HIV-1 infection.

描述（由申请人提供）：CCR5 表达的缺乏与 HIV-1 感染的抵抗力相关。这种缺陷是由于 CCR5 基因 (CCR5 32) 中 32bp 缺失的纯合性造成的。已鉴定出数名缺乏 CCR5 表达 (CCR5-/-) 但 HIV-1 血清阳性的 CCR5 32 个体。该病毒如何克服 CCR5 32 的保护作用尚未被描述，我们已经在六名 HIV+ CCR5-/- 患者中对此进行了研究。我们证明，从暴露/未感染 (EU) CCR5-/- 个体中分离的外周血单核细胞 (PBMC) 表达截短的 CCR5 32 蛋白。相比之下，四名暴露/感染 (EI) CCR5-/- 患者缺乏 CCR5 32 蛋白表达，另外两名患者表达水平较低。脉冲追踪实验证明该蛋白在三个 HIV+CCR5-/- 个体中不稳定。另外两个在启动子区域存在突变，该突变与 CCR5 32 蛋白的低翻译相关。 CCR5 32 蛋白表达缺失或低与表面 CXCR4 增加相关。然而，我们的结果表明，HIV+CCR5-/-患者的抵抗力丧失不能仅仅归因于CXCR4水平的升高。重组 CCR5 32 蛋白的表达恢复了三个 HIV+ CCR5-/- PBMC 样本中的保护作用，但未能恢复来自另外三个 HIV+ CCR5-/- 个体的样本中的保护作用。建议研究 HIV+CCR5-/- 受试者中 CCR5 32 表达缺失的两种潜在机制； 1) 由感染病毒引起的反式效应或 2) 顺式宿主效应，最终导致新信号传导途径的产生和抗性表型的丧失。我们发现从两名独立的 CCR5-/- 患者克隆的包膜糖蛋白 (Envs) 显示出扩大的辅助受体使用。我们假设从 HIV+CCR5-/- 个体中分离出的主要 HIV-1 毒株具有独特的结构决定因素，使它们能够绕过 CCR5 32 突变的保护作用。尽管病毒载量轻微，但 CD4+ T 细胞快速丢失是这些 HIV+CCR5-/- 患者慢性感染的特征。我们方法的新颖性在于这些初级分离株在体内感染 CCR5-/- 细胞并在其中复制的独特性质。该提案的总体目标是确定 CCR5 32 保护作用丧失的分子基础。为此，我们将表征来自 CCR5-/- 患者的主要 HIV-1 分离株，评估 Env 融合性、细胞凋亡诱导能力、辅助受体识别模式，并且我们将确定 CCR5 32 蛋白 C 末端的新 31 个残基的作用。公共卫生相关性：本申请旨在调查受感染的同性恋个体中携带的 HIV 病毒类型。由于艾滋病毒是导致获得性免疫缺陷综合症（艾滋病）的病毒，因此这些艾滋病毒病毒的基本知识将为艾滋病发病机制提供重要的新见解。该项目与公共卫生非常相关，因为拟议研究的结果将为设计阻止 HIV-1 感染的药物提供新的机制方法。