Cross-Protective Immunity to African Trypanosomes

对非洲锥虫的交叉保护性免疫

• 批准号: 8414204
• 负责人: John M. Mansfield
• 金额: $ 18.17万
• 依托单位: UNIVERSITY OF WISCONSIN-MADISON
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-01-15 至 2013-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8414204
• 关键词: Achievement; Africa; Africa South of the Sahara; African; African Trypanosomiasis; Amino Acid Sequence; Animals; Antigenic Variation; Antigens; B-Lymphocytes; Blood; Blood Vessels; Brain; C-terminal; Clinical; Coupled; DNA; Development; Diagnosis; Disease; Elements; Generations; Genes; Genetic Transcription; Goals; HSV glycoprotein C; Host resistance; Human; Immune; Immune response; Immunity; Immunization; Immunotherapeutic agent; Individual; Infection; Infection Control; Interferons; Laboratories; Link; Macrophage Activation; Mediating; Membrane Glycoproteins; Monitor; Mus; N-terminal; Organism; Parasite Control; Parasites; Patients; Peptide Sequence Determination; Peptides; Preventive; Production; Recombinants; Relative (related person); Research Infrastructure; Resistance; Resolution; Site; Specificity; T cell response; T memory cell; T-Lymphocyte; Testing; Th1 Cells; Therapeutic; Therapeutic Intervention; Time; Tissues; Trypanosoma; Trypanosomiasis; Vaccines; Variant; Work; disorder control; glycoprotein structure; immune clearance; innovation; microbial; novel; novel strategies; pathogen; prevent; protein aminoacid sequence; research study; response; success; tool

DESCRIPTION (provided by applicant): All successful microbial pathogens evade or alter host immune responses. Arguably the most well-known example of immune evasion by parasites is antigenic variation of the variant surface glycoprotein (VSG) coat by the African trypanosomes, which prevents immune elimination of the organisms from vascular and- extra vascular tissue sites of infection. VSG-specific B cell responses are associated with, and largely limited to, control of Parasites in the blood, but are VSG-specific Th1 cell responses that are functionally and genetically linked to relative resistance against trypanosomes. This resistance is mediated by IFN-? activation of macrophages for production of the trypanocidal factors RNI, ROS and TNFa In the extra vascular tissues. Thus, IFN-? production is critical for host survival but is largely dependent on Th1 cell recognition of VSG-specific epitomes. Ultimately, however, antigenic variation of the VSG coat leads to immune escape and trypanosome infections are invariably fatal for their hosts. Two recent achievements in our laboratory have opened a window of opportunity for immunological control or cure of African trypanosomiasis. The first is a discovery that temporally protective VSG-specific T cell responses are directed exclusively at highly variable N-terminal micro domains within the VSG molecule, and are not directed at residues within the highly conserved -terminal domain. Thus, VSG specific T cell responses are variant specific and do not cross-react with other VSGs that express homologous C-terminal domain sequences. This information provides a unique opportunity to artificially direct Th1 cell responses to conserved VSG sequences and to promote control or cure of infection. The second discovery is that by expressing an exogenous eGFP gene from a stable transcription site in trypanosome DNA, we are able for the first time to visualize viable trypanosomes within the extra vascular tissues and to monitor the efficacy of immunotherapeutic treatments for host resistance. These novel elements form the infrastructure for this proposal. The central hypothesis to be tested is that activation of T cell responses to conserved C-terminal residues of the trypanosome variant surface glycoprotein (VSG) molecule will promote variant cross- protective immunity to infection, leading to control or cure of disease. Aim 1 encompasses experiments in which natural, altered natural, recombinant and synthetic conserved C-terminal VSG subsequences will be used to provoke variant cross-specific Th1 cell responses in na¿ve mice. Immunized animals subsequently will be infected with different trypanosome variants expressing the conserved VSG residues. This aim will provide "proof of principle" for the central hypothesis. Aim 2 extends the work plan to experiments that have clinical translational potential. Treatment of mice already infected with African trypanosomes will be accomplished by immunization with invariant VSG cross- protective protein sequences identified in Aim 1. Animals will be monitored for resolution of infection coupled with activation of appropriate T cells with specificity for variant cross-protective sequences. This aim provides a hypothetical "real world test" for the central hypothesis, in which patients diagnosed with the disease could be rescued by intervention therapy. The ability to induce cross-variant specific T cell responses and parasite elimination in individuals already infected would have tremendous impact on clinical disease in Africa. Thus, the experiments proposed here provide, for the first time, a novel approach to the control or cure of a Third World disease that has proven intractable to every form of preventive or clinical therapy to date.

描述（由申请人提供）：所有成功的微生物病原体逃避或改变宿主的免疫反应。可以说，寄生虫免疫逃避的最著名的例子是非洲锥虫的变异表面糖蛋白（VSG）外壳的抗原变异，这阻止了从血管和血管外组织感染部位免疫消除生物体。vsg特异性B细胞反应与血液中寄生虫的控制有关，并且在很大程度上仅限于此，但vsg特异性Th1细胞反应在功能和遗传上与对锥虫的相对抗性相关。这种耐药性是由IFN-？激活巨噬细胞在血管外组织中产生锥虫因子RNI， ROS和TNFa。因此,干扰素- ?它的产生对宿主的生存至关重要，但很大程度上依赖于Th1细胞对vsg特异性表集的识别。然而，最终，VSG外壳的抗原变异导致免疫逃逸，锥虫感染对其宿主总是致命的。我们实验室最近取得的两项成果为非洲锥虫病的免疫控制或治疗打开了一扇机会之窗。第一个发现是，VSG特异性T细胞的暂时性保护性反应仅针对VSG分子内高度可变的n端微结构域，而不针对高度保守的n端结构域内的残基。因此，VSG特异性T细胞反应是变异特异性的，不会与其他表达同源c末端结构域序列的VSG交叉反应。这一信息为人工引导Th1细胞对保守VSG序列的反应并促进感染的控制或治愈提供了独特的机会。第二个发现是，通过从锥虫DNA的稳定转录位点表达外源性eGFP基因，我们首次能够在血管外组织中可视化活的锥虫，并监测免疫治疗对宿主抗性的效果。这些新颖的元素构成了这个方案的基础设施。要验证的中心假设是，T细胞对锥虫变异表面糖蛋白（VSG）分子的保守c端残基的反应激活将促进对感染的变异交叉保护免疫，从而控制或治愈疾病。目的1包括天然的、改变的天然的、重组的和合成的保守的c端VSG子序列将在na - ve小鼠中引起变异的交叉特异性Th1细胞反应。免疫后的动物将感染表达保守VSG残基的不同锥虫变体。这一目标将为中心假设提供“原理证明”。目标2将工作计划扩展到具有临床转化潜力的实验。对已经感染非洲锥虫的小鼠的治疗将通过免疫接种在Aim 1中鉴定的不变的VSG交叉保护蛋白序列来完成。将对动物进行监测，以解决感染，并激活具有变异交叉保护序列特异性的适当T细胞。这一目标为中心假设提供了一个假想的“现实世界测试”，即被诊断患有这种疾病的患者可以通过干预治疗得到拯救。在已经感染的个体中诱导交叉变异特异性T细胞反应和消除寄生虫的能力将对非洲的临床疾病产生巨大影响。因此，这里提出的实验首次提供了一种控制或治愈第三世界疾病的新方法，这种疾病迄今已被证明对任何形式的预防或临床治疗都难以治愈。