EIAV Control by DNA Vaccine-Induced CTL

DNA 疫苗诱导的 CTL 控制 EIAV

• 批准号: 7087250
• 负责人: ROBERT H MEALEY
• 金额: $ 21.5万
• 依托单位: WASHINGTON STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-06-01 至 2008-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7087250
• 关键词: MHC class I antigen; chimeric proteins; cytotoxic T lymphocyte; disease carrier state; epitope mapping; equine infectious anemia virus; horses; human immunodeficiency virus 1; leukocyte activation /transformation; pathologic process; vaccine development; vaccine evaluation; vector vaccine; viral vaccines; virus load; virus replication

DESCRIPTION (provided by applicant): It is clear that virus-specific CTL are critically important in limiting lentiviral replication. Despite the importance of CTL, T lymphocyte responses ultimately fail to control HIV-1 replication and progression to AIDS and death results. Protective vaccines will undoubtedly need to induce CTL, but development of such vaccines is hampered because the correlates of T lymphocyte-mediated protection are not known. Specific knowledge gaps include how to induce and maintain protective CTL in an MHC class I disparate population, the specific epitopes recognized by protective CTL, the qualitative characteristics (i.e., functional avidity) of protective CTL, and whether protection can occur in the absence of neutralizing antibody. The overall goal of the proposed research is to develop immunization methods that induce protective anti-lentiviral CTL responses in individuals with diverse MHC class I backgrounds. The lentiviral system under study is EIAV in horses. Most horses control EIAV replication within a year and remain persistently infected inapparent carriers. In immunocompetent horses, CTL can be demonstrated concurrent with clearance of the initial viremia, prior to the appearance of neutralizing antibody, indicating that CTL are critical in EIAV control. ElAV-specific CTL epitopes have been identified in Gag, Pol, Env, Rev, and S2, with Gag-specific CTL occurring in a high percentage of infected horses. Importantly, four CTL epitope clusters occur in the p15 matrix and p26 capsid proteins of Gag. These epitope clusters contain conserved epitopes that are recognized by high avidity CTL from inapparent carrier horses with diverse MHC class I alleles. The experiments outlined in this proposal will determine if a DNA vaccine encoding conserved Gag-specific epitope clusters, augmented with a plasmid expressing an equine IL-2/lgG fusion protein, will induce high avidity Gag-specific CTL in horses with diverse MHC class I alleles. Additional experiments will determine whether or not these horses are subsequently protected against EIAV challenge. This research is consistent with the exploratory/developmental nature of the R21 mechanism as described in PA-03-082 because it evaluates a novel strategy to induce protective anti-lentiviral CTL in MHC class I disparate individuals using a nucleic acid vaccine. Because our vaccine constructs will not encode envelope proteins, protective effects will occur in the absence of neutralizing antibody. Accomplishing these aims should help define the correlates for CTL-induced protection against lentivirus challenge in a diverse population. The information obtained from the proposed studies should have implications for HIV-1 vaccine design, where experiments of this type may be more difficult.

描述（由申请人提供）：很明显，病毒特异性CTL对于限制慢病毒复制至关重要。尽管 CTL 很重要，但 T 淋巴细胞反应最终无法控制 HIV-1 的复制以及进展为艾滋病和死亡结果。毫无疑问，保护性疫苗需要诱导 CTL，但此类疫苗的开发受到阻碍，因为 T 淋巴细胞介导的保护的相关性尚不清楚。具体的知识差距包括如何在 MHC I 类不同群体中诱导和维持保护性 CTL、保护性 CTL 识别的特定表位、保护性 CTL 的定性特征（即功能亲和力）以及在没有中和性的情况下是否可以发生保护性抗体。 拟议研究的总体目标是开发免疫方法，在具有不同 MHC I 类背景的个体中诱导保护性抗慢病毒 CTL 反应。正在研究的慢病毒系统是马的 EIAV。大多数马在一年内控制了 EIAV 的复制，并保持持续感染的隐性携带者状态。在免疫功能正常的马中，在中和抗体出现之前，可以证明 CTL 与初始病毒血症的清除同时发生，表明 CTL 在 EIAV 控制中至关重要。 ElAV 特异性 CTL 表位已在 Gag、Pol、Env、Rev 和 S2 中鉴定出，Gag 特异性 CTL 出现在感染马中的比例很高。重要的是，四个 CTL 表位簇出现在 Gag 的 p15 基质和 p26 衣壳蛋白中。这些表位簇包含保守表位，这些表位可被来自具有多种 MHC I 类等位基因的隐性携带者马的高亲和力 CTL 识别。 本提案中概述的实验将确定编码保守的 Gag 特异性表位簇的 DNA 疫苗，用表达马 IL-2/IgG 融合蛋白的质粒增强，是否会在具有多种 MHC I 类的马中诱导高亲和力的 Gag 特异性 CTL等位基因。额外的实验将确定这些马随后是否受到 EIAV 攻击的保护。这项研究与 PA-03-082 中描述的 R21 机制的探索/发展性质一致，因为它评估了一种使用核酸疫苗在 MHC I 类不同个体中诱导保护性抗慢病毒 CTL 的新策略。由于我们的疫苗结构不会编码包膜蛋白，因此在没有中和抗体的情况下会产生保护作用。实现这些目标应有助于确定 CTL 在不同人群中诱导的针对慢病毒挑战的保护作用的相关性。从拟议研究中获得的信息应该会对 HIV-1 疫苗设计产生影响，因为此类实验可能更加困难。