A NON-HUMAN PRIMATE MODEL OF TICK-IMMUNITY

蜱免疫的非人类灵长类动物模型

• 批准号: 7716309
• 负责人: SUKANYA NARASIMHAN
• 金额: $ 1.39万
• 依托单位: TULANE UNIVERSITY OF LOUISIANA
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-07-21 至 2009-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7716309
• 关键词: Animal Model; Animals; Antigens; Arthropod Vectors; Autopsy; Babesiosis; Biopsy; Black-legged Tick; Borrelia; Borrelia burgdorferi; Bovine Anaplasmosis; Communicable Diseases; Computer Retrieval of Information on Scientific Projects Database; Control Groups; DNA analysis; Funding; Grant; Humoral Immunities; Immunity; Impairment; Institution; Lyme Disease; Macaca mulatta; Medicine; Modeling; Mus; Numbers; Order Spirochaetales; Pilot Projects; Placement; Play; Primates; Process; RNA; Redness; Research; Research Personnel; Resistance; Resources; Rest; Rickettsia Infections; Role; Salivary; Salivary Glands; Salivary Proteins; Serum; Site; Skin; Source; Tick Infestations; Tick-Borne Encephalitis; Ticks; Time; Tissues; United States National Institutes of Health; Universities; Vaccines; Week; Weight; comparative; feeding; nonhuman primate; pathogen; response; transmission process; vector

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Ixodes scapularis is an important arthropod vector for pathogens responsible for Lyme disease, rickettsial disease, anaplasmosis, babesiosis, and tick borne encephalitis. There is an unmet need for safe and effective vaccines against these pathogens. Vaccines directed against the tick vector would potentially target multiple pathogens transmitted by the tick. The vertebrate host, upon repeated tick infestation, rejects ticks within 12-24 h and also blocks pathogen transmission. Host immunity directed against crucial tick salivary antigens presumably plays a pivotal role in tick rejection and in the consequent impairment of pathogen transmission. While the phenomenon of acquired tick immunity provides an opportunity to define salivary proteins critical for tick feeding and pathogen transmission, animal models that can demonstrate both tick immunity and viable pathogen transmission are not available. With a focus of Borrelia burgdorferi, the agent of Lyme disease, the current pilot proposal assessed if non-human primates (NHP) might serve such an animal model and enhance efforts to identify vaccines to block tick feeding and pathogen transmission. In Specific Aim 1, two NHPs (Macaca mulatta) were repeatedly infested three times with 10-20 pathogen-free I. scapularis ticks with a three-week resting period between each tick infestation. Optimization of tick placement, and tick infestation studies were conducted over the first 6 months of the funding period at the Tulane National Primate Research Center. The pilot study, albeit limited by the numbers of animals, did not reveal the hallmarks of acquired tick immunity. The ticks successfully engorged as seen by comparable tick attachment and tick weights at all infestations. No significant redness was observed at tick feeding sites upon repeated tick infestations. These observations suggested that NHPs, like mice, might not elicit resistance to ticks. However, histological analysis of the skin biopsies of the tick-feeding sites and reactivity of the sera obtained from these tick-infested animals to tick salivary antigens will be essential. These analyses are pending and are being conducted at the Sections of Comparative Medicine and Infectious Diseases, Yale University. In Specific Aim 2, we challenged the two repeatedly tick-infested NHPs from Aim 1 with 10 Borrelia-infected I.scapularis ticks. Two na¿ve NHPs were similarly challenged with Borrelia-infected ticks. Comparable tick engorgements were observed in both groups. Borrelia burden in the midguts and salivary glands of the fed ticks was also comparable in both groups. However, culture of skin biopsies of the NHPs at 2, 4, 6 and 8 weeks showed no viable spirochetes in the experimental group that was repeatedly infested with ticks. In the control group, one animal demonstrated viable spirochetes. This suggested that upon repeated infestation, NHPs might elicit humoral immunity against tick salivary antigens critical for pathogen transmission. All the animals were sacrificed at the end of 8 weeks and tissues relevant for Lyme disease necropsied for RNA and DNA analysis. These tissues are being processed for quantitative assessment of spirochete burden at the Section of Infectious Diseases, Yale University and studies nearing completion. These results will confirm the NHPs response to tick infestations and reveal the utility of the NHP model to examine tick antigens critical for tick feeding and pathogen transmission.

该子项目是利用该技术的众多研究子项目之一 资源由 NIH/NCRR 资助的中心拨款提供。子项目和 研究者 (PI) 可能已从 NIH 的另一个来源获得主要资金， 因此可以在其他 CRISP 条目中表示。列出的机构是 对于中心来说，它不一定是研究者的机构。 肩胛硬蜱是导致莱姆病、立克次体病、无形体病、巴贝斯虫病和蜱传脑炎的病原体的重要节肢动物媒介。针对这些病原体的安全有效的疫苗的需求尚未得到满足。针对蜱虫媒介的疫苗可能会针对蜱虫传播的多种病原体。脊椎动物宿主在受到蜱虫反复侵扰后，会在 12-24 小时内排斥蜱虫，并阻止病原体传播。针对关键蜱唾液抗原的宿主免疫可能在蜱排斥和随后的病原体传播损害中发挥关键作用。虽然获得性蜱免疫现象提供了一个机会来定义对蜱进食和病原体传播至关重要的唾液蛋白，但目前还没有能够证明蜱免疫和可行病原体传播的动物模型。 目前的试点提案以莱姆病的病原体伯氏疏螺旋体为重点，评估非人类灵长类动物 (NHP) 是否可以作为此类动物模型，并加大力度寻找疫苗来阻止蜱虫进食和病原体传播。在具体目标 1 中，两只 NHP（Macaca mulatta）被 10-20 只无病原体的肩胛 I. scapularis 蜱重复感染 3 次，每次蜱感染之间有 3 周的休息期。杜兰国家灵长类动物研究中心在资助期的前 6 个月内进行了蜱虫安置优化和蜱虫感染研究。 该试点研究尽管受到动物数量的限制，但并未揭示获得性蜱免疫的特征。从所有感染处的蜱附着力和蜱重量可看出，蜱成功地充血。在蜱虫反复侵扰后，蜱虫进食地点没有观察到明显的红色。这些观察结果表明，NHP 与小鼠一样，可能不会引起对蜱虫的抵抗力。然而，对蜱进食部位的皮肤活检以及从这些蜱感染的动物获得的血清对蜱唾液抗原的反应性进行组织学分析将是至关重要的。这些分析正在等待中，并正在耶鲁大学比较医学和传染病部门进行。在具体目标 2 中，我们用 10 只感染肩胛疏螺旋体的蜱对目标 1 中的两个反复感染蜱的 NHP 进行了挑战。两个未接触过的 NHP 也同样受到了感染疏螺旋体的蜱虫的攻击。两组中都观察到了类似的蜱充血情况。两组喂食蜱的中肠和唾液腺中的疏螺旋体负担也相当。 然而，第2、4、6和8周时NHP的皮肤活检培养显示，在反复感染蜱虫的实验组中没有存活的螺旋体。在对照组中，一只动物表现出可存活的螺旋体。这表明，在反复感染后，NHP 可能会引发针对蜱唾液抗原的体液免疫，这对病原体传播至关重要。 8周结束时处死所有动物，并对与莱姆病相关的组织进行尸检以进行RNA和DNA分析。耶鲁大学传染病科正在处理这些组织，用于螺旋体负荷的定量评估，研究已接近完成。 这些结果将证实 NHP 对蜱感染的反应，并揭示 NHP 模型在检查对蜱进食和病原体传播至关重要的蜱抗原方面的实用性。