MHC-Ib restricted T cell responses against Listeria monocytogenes

描述(由申请人提供)：1单核细胞增生性李斯特氏菌(Lm)是B类优先病原体，可引起2种食源性疾病的暴发，发病率和死亡率都很高。CD8+T细胞必须识别感染细胞表面MHC-I蛋白结合的抗原，从而激活T细胞，获得5种保护性效应功能，才能实现对LM的灭菌免疫。经典MHC-I蛋白(MHC-Ia)的研究已有60年的历史，但对大多数非经典MHC-I蛋白7(MHC-Ib)的研究相对较少。我们建立了一种MHC-Ia缺陷的小鼠LM感染模型，以研究8个MHC-Ib限制性T细胞在清除细胞内细菌病原体中的作用。我们的中心假设是，LM免疫的小鼠含有识别新的MHC-Ib10蛋白的记忆CD8+T细胞，这些T细胞在清除继发性LM感染方面发挥着重要作用。11在初步研究中，我们发现在一种新的(不是M3)MHC-Ib蛋白的背景下识别抗原的CD8+T细胞在LM感染期间被激活。我们已经确定了9个小鼠MHC-Ib基因，它们可能表达在感染过程中作为抗原14递呈分子的蛋白质。在这一应用中，我们建议：1)建立一个由15个人巨噬细胞样细胞组成的小组，每个细胞分别转染9个候选MHC-Ib基因；2)16个使用MHC-Ib转染体来确定在LM感染过程中有多少不同的MHC-Ib蛋白能够向T细胞递呈抗原。这些研究将有助于确定18个MHC-Ib限制性T细胞在针对LM的保护性免疫反应中的作用，并可能有助于识别所有细胞内细菌病原体的新类抗原。由于大多数MHC-Ib蛋白是非多态的，与MHC-Ib蛋白结合的抗原可能被给定群体中的大多数人识别，如果不是所有人识别的话。这使得MHC-Ib 22抗原特别有吸引力被包括在疫苗中，旨在预防23细胞内细菌病原体的感染。与公共卫生相关：在试图设计疫苗以防止感染可以在宿主细胞内生存的细菌时，面临的一个重大障碍是识别所有人都能识别的抗原，而不考虑他们的血型(MHC单倍型)。在这项研究中，我们将描述识别单核细胞增多性李斯特菌与MHC-Ib蛋白结合的抗原的T细胞亚群，MHC-Ib蛋白是一类在小鼠和人类中都是非多态的(在个体之间几乎没有变化)的蛋白质。这些研究有可能导致新的治疗策略，以防止各种细胞内细菌的感染，包括流行的人类病原体，如结核分枝杆菌和沙眼衣原体。

DESCRIPTION (provided by applicant): 1 Listeria monocytogenes (Lm) is a category B priority pathogen that causes outbreaks of 2 foodborne illness with a high incidence of morbidity and mortality. To achieve sterilizing 3 immunity against Lm, CD8+ T cells must recognize antigens bound to MHC-I proteins on the 4 surface of infected cells, an event that results in activation of the T cells and acquisition of 5 protective effector functions. Classical MHC-I proteins (MHC-Ia) have been studied for 6 decades, however, comparatively little is known about most of the non-classical MHC-I proteins 7 (MHC-Ib). We developed a MHC-Ia deficient mouse model of Lm infection to study the role of 8 MHC-Ib restricted T cells in the clearance of intracellular bacterial pathogens. Our central 9 hypothesis is that Lm-immune mice contain memory CD8+ T cells that recognize novel MHC-Ib 10 proteins, and that these T cells play a significant role in the clearance of secondary Lm infection. 11 In preliminary studies, we showed that CD8+ T cells that recognize antigen in the context of a 12 novel (not M3) MHC-Ib protein are activated during Lm infection. We have identified nine 13 murine MHC-Ib genes as likely candidates to express proteins that could serve as antigen 14 presenting molecules during infection. In this application, we propose to: 1) develop a panel of 15 human macrophage-like cells transfected with each of the nine candidate MHC-Ib genes and 2) 16 use the MHC-Ib transfectants to determine how many different MHC-Ib proteins are capable of 17 presenting antigen to T cells during Lm infection. These studies will help to define the role of 18 MHC-Ib restricted T cells in protective immune responses against Lm and may facilitate the 19 identification of new classes of antigens for all intracellular bacterial pathogens. Since most 20 MHC-Ib proteins are non-polymorphic, antigens that bind to MHC-Ib proteins are likely to be 21 recognized by most, if not all of the individuals in a given population. This makes MHC-Ib 22 antigens particularly attractive candidates for inclusion in vaccines designed to protect against 23 infection with intracellular bacterial pathogens. PUBLIC HEALTH RELEVANCE: One of the significant hurdles faced in trying to design vaccines to protect against infection with bacteria that can survive inside host cells is the identification of antigens that will be recognized by all individuals, regardless of their blood type (MHC haplotype). In this study, we will characterize a subset of T cells that recognize antigens derived from Listeria monocytogenes bound to MHC-Ib proteins, a class of proteins that is non- polymorphic (displays little variation among individuals) in both mice and humans. These studies have the potential to lead to new therapeutic strategies to protect against infections with a variety of intracellular bacteria, including prevalent human pathogens such as Mycobacteria tuberculosis and Chlamydia trachomatis.