Identification of T-Cell Immunogens in Anaplasma

描述（由申请人提供）：CD4+ T淋巴细胞介导的MHC ii类限制性反应是对无虫科蜱传病原体的免疫控制的核心。CD4+ T淋巴细胞的启动和扩增是产生针对细菌表面的高亲和力中和性IgG抗体和有效的吞噬细胞激活导致细菌死亡所必需的。这项研究的目标是鉴定诱导免疫所需的T细胞反应的病原体蛋白。迄今为止，只有四种T细胞免疫刺激分子在边缘无原体中被鉴定出来，在无原体科的相关人类病原体中没有。我们将利用一种全面的策略来解决这一知识差距，以识别外膜蛋白，这些蛋白可以启动初始CD4+ T淋巴细胞并诱导免疫和保护动物的回忆记忆T细胞反应。在项目的第一部分中，我们建议使用外膜生化分离与基因组分析相结合的方法来识别T细胞应答的靶点。在第1部分的结论中，我们期望已经鉴定出在边缘芽孢杆菌菌株中保守的携带CD4+ T细胞表位的新型外膜蛋白。无形体科物种间存在分子和免疫学同源物，表明研究结果具有广泛的应用价值，有助于增进对人类疾病的认识和控制。

DESCRIPTION (provided by applicant): MHC class II-restricted responses mediated by CD4+ T lymphocytes are central to immune control of the tick-borne pathogens of the Family Anaplasmataceae. Priming and expansion of CD4+ T lymphocytes is required for development of high affinity neutralizing IgG antibodies directed against the bacterial surface and for efficient phagocyte activation leading to bacterial killing. The goal of the research is to identify the pathogen proteins that induce the T cell responses required for immunity. To date, only four T cell immunostimulatory molecules have been identified in Anaplasma marginale, the type species, and none in the related human pathogens within the Anaplasmataceae. We will address this knowledge gap using a comprehensive strategy to identify outer membrane proteins that prime naive CD4+ T lymphocytes and induce recall memory T cell responses of immunized and protected animals. In part 1 of the project, we propose to use a combination of biochemical fractionation of outer membranes combined with genomic analysis to identify the targets of the T cell response. At the conclusion of part 1, we expect to have identified novel outer membrane proteins bearing CD4+ T cell epitopes conserved among A. marginale strains. The presence of molecular and immunological orthologs among species in the Family Anaplasmataceae indicates that the research results should be broadly applicable and enhance understanding and control of human diseases. In part 2 of the project, we will examine the requirement for linked recognition of covalently associated outer membrane proteins in generating immunity. A. marginale outer membrane proteins are covalently linked by extensive disulfide bonding. How this covalent bonding affects generation of immunity is unknown. The observation that Major Surface Protein (MSP) 1a-specific CD4+ T cells provide help for B-lymphocytes to secrete antibody to the covalently bound MSPlb suggests that the native association of outer membrane proteins can be critical in inducing protective responses. We hypothesize that this "linked recognition" of CD4+ T cell and B cell epitopes from different outer membrane proteins can be mimicked using chimeric multiple epitope constructs. At the conclusion of part 2, we expect to have determined if linked recognition between covalently bound outer membrane proteins, using MSPla and MSPlb as a model complex immunogen, can be represented by a chimeric epitope construct.