EPITOPE DELIVERY, IMMUNODOMINANCE AND VACCINE EFFICACY

描述(摘自申请者摘要)：针对单核细胞增多性李斯特菌的保护性免疫反应用于研究细胞免疫对胞内细菌的一般特征。在BALB/c小鼠体内，已分离到KD限制性的李斯特菌特异性CD8CTL。来自吞噬细胞空泡中分泌的李斯特溶素O(LLO)和胞浆中大量分泌的P60分子的多肽已被确定为CTL靶标。CTL频率分析表明，LLO衍生的决定簇LLO 91-99是免疫显性的。我们推测，吞噬空泡中分泌的LLO是LLO 91-99肽免疫优势的一个贡献因素。在具体目标I中，描述了将确定吞噬细胞空泡内特定多肽的分泌是否是其免疫优势的促成因素的研究。在这些研究中，我们将使用单核细胞增多性乳杆菌突变体，其中KD结合纳米肽(通常是酪氨酸)中第2位的锚定残基已被苯丙氨酸取代。突变体保留了野生型表型，但用这些菌株免疫后，特异性CTL不会被刺激到突变的多肽序列。我们将使用这些突变体将特定的李斯特菌衍生多肽运送到单核细胞增多性李斯特菌感染细胞的吞噬空泡或细胞质中，以确定这些初始位置对后续CTL反应的影响。单核细胞增多性乳杆菌被认为是传递候选抗原和刺激特异性细胞免疫的载体。疫苗载体传递候选抗原的价值在一定程度上取决于在现有抗媒介免疫的环境中特异性刺激免疫反应的能力。在特定目标II中，我们将确定单核细胞增多性李斯特菌作为疫苗载体的效用，并评估已确定疫苗载体现有免疫水平的动物的多肽特异性免疫发展情况。我们将评估多肽特异性效应细胞和记忆细胞反应的发展。这些研究的结果将指导新疫苗载体的总体开发战略，并确定在疫苗载体的免疫学状况未知的人群中使用它们的限制。

DESCRIPTION (adapted from applicant's abstract): The protective immune response to L. monocytogenes is used to investigate general features of cell-mediated immunity to intracellular bacteria. In BALB/c mice, Listeria-specific CD8+ CTL have been isolated which are Kd restricted. Peptides from listeriolysin O (LLO) a molecule secreted in the phagocytic vacuole, and p60, a molecule that is abundantly secreted in the cytoplasm, have been identified as CTL targets. CTL frequency analysis shows that the LLO-derived determinant, LLO 91-99, is immunodominant. We hypothesize that secretion of LLO within the phagocytic vacuole is a contributing factor to the immunodominance of the LLO 91-99 peptide. In Specific Aim I, studies are described that will determine if secretion of defined peptides within the phagocytic vacuole is a contributing factor to their immunodominance. For these studies, we will use L. monocytogenes mutants in which the anchor residue at position 2 within the Kd-binding nanomer peptide (normally a tyrosine) has been replaced by phenylalanine. The mutants retain the wildtype phenotype, yet following immunization with these strains, specific CTL are not stimulated to the mutant peptide sequence. We will use these mutants to deliver specific Listeria-derived peptides to the phagocytic vacuole or the cytoplasm of the L. monocytogenes infected cell in order to determine the influence of these initial locations on the subsequent CTL response. L. monocytogenes has been proposed as a vector to deliver candidate antigens and stimulate specific cell-mediated immunity. The value of vaccine vectors for delivery of candidate antigens depends in part on the ability to specifically stimulate the immune response in an environment of existing anti-vector immunity. In Specific Aim II, we will determine the utility of L. monocytogenes as a vaccine vector and assess the development of peptide specific immunity in animals that have defined levels of existing immunity to the vaccine vector. We will assess the development of peptide specific effector cell and memory cell responses. The results from these studies will guide strategies for the general development of novel vaccine carriers as well as to define the limits of their use within a population whose immunologic status to the vaccine carrier is unknown.