Targeted Prevention of Human Ehrlichiosis

人类埃利希体病的针对性预防

基本信息

批准号：
9990077
负责人：
YASUKO RIKIHISA
金额：
$ 39.38万
依托单位：
OHIO STATE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2021
资助国家：
美国
起止时间：
2021-08-17 至 2026-07-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/9990077
关键词：
Adverse effects Amblyomma Anaplasma Animal Model Anti-Infective Agents Antibiotics Antibodies Antibody Response Apoptosis Autophagocytosis Bacteria Bacterial Outer Membrane Proteins Binding Blood Canis familiaris Cells Centers for Disease Control and Prevention (U.S.)Cessation of life Cloning Combined Vaccines Country DNA DNA Sequence DNA Vaccines Data Development Doxycycline Ehrlichia Ehrlichia chaffeensis Ehrlichiosis Emerging Communicable Diseases Exposure to FDA approved Formulation Future Genetic Transcription Geographic Locations Goals High Prevalence Human Immune response Immunization Immunize Incidence Infection Infectious Agent Interferon Type II Jet Injections Knowledge Life Lipoproteins Mammalian Cell Mammals Measures Mediating Membrane Proteins Methods Military Personnel Mission Mus Needles Nutrient Outcome Pilum Police Prevention Process Proteins Public Health Publishing Receptor Cell Recombinants Reporting Rickettsia Rickettsia Infections Risk Sentinel Surface Symptoms T cell response T-Lymphocyte Testing Th1 Cells Tick-Borne Diseases Ticks Toxic effect Type IV Secretion System Pathway United States National Institutes of Health VDAC1 gene Vaccines Vector-transmitted infectious disease Wild Animals Work Zoonoses cell mediated immune response disability evidence base expression vector flu geographic risk high risk improved monocyte mortality neutralizing antibody pathogen plasmid DNA prevent prophylactic response tick bite tick transmission tick-borne tick-borne pathogen transmission process vaccine candidate vaccine delivery vaccine development

项目摘要

The incidence of tick-borne diseases has risen dramatically in the past two decades, and continues to rise. Human monocytic ehrlichiosis caused by Ehrlichia chaffeensis (Ech) is one of the most prevalent, life- threatening, emerging tick-borne zoonoses in the US. Ech is an obligatory intracellular bacterium of the order Rickettsiales. Therapy of choice is the broad-spectrum antibiotic doxycycline, which is effective only if initiated early. Currently there is no FDA-approved vaccine for Ech. Our long-term goal is to develop an evidence- based vaccine approach to effectively protect humans by targeting multiple critical steps of the rickettsial infection cycle. Toward this goal, we identified four Ech surface-exposed proteins that have known functions required for Ech survival, and that also lack homology to human proteins, OMP-1/P28, Entry triggering protein of Ehrlichia (EtpE), and VirB2. OMP-1/P28s are immunodominant surface-exposed outer membrane proteins that have porin activity essential for bacterial nutrient acquisition. P28 and OMP-1B are predominantly expressed in mammals and ticks, respectively. EtpE is an invasin that uses its C-terminus (EtpE-C) to bind the host cell receptor to trigger Ech entry. We have shown that the type IV secretion system (T4SS) is essential for Ech survival within the host cell. VirB2 is a T4SS pilus protein that is part of the T4SS machinery. Immunization of mice with recombinant P28, EtpE, or VirB2 proteins generated Ech-specific antibody responses that prevented Ech infection. These data support our premise that these proteins serve as rational vaccine candidates for targeting non-overlapping processes in Ech infection of mammalian host cells. DNA vaccines offer a number of potential advantages over traditional vaccines, including the stimulation of both humoral and T-cell-mediated responses, improved vaccine stability, the absence of any infectious agent, and the relative ease of packaging multi-components and large-scale manufacture. We showed the feasibility of an Ech DNA vaccine in dogs by safely immunizing dogs with the DNA vaccines by percutaneous needle-free jet injection and demonstrating humoral and cell-mediated immune responses to the DNA vaccines. Our hypothesis is immunization with plasmid DNA vaccine encoding P28, OMP-1B, EtpE and VirB2 singly or in combination prevents Ech transmission from ticks to mammals. To test this hypothesis, our Specific Aims are: 1. To construct DNA vaccines encoding P28, OMP-1B, EtpE-C, and VirB2, determine the development of humoral and cell-mediated immune responses in immunized mice, and evaluate protection of immunized mice from infection with Ech cultured in tick cells. 2. To test if immunization of dogs with P28, OMP-1B, EtpE-C and VirB2 can prevent Ech transmission from infected ticks. The immediate outcomes of the proposed studies will be to provide proof-of-principle for a DNA vaccine approach to the Ech vaccine candidates for blocking of Ech transmission from ticks to dogs. The long-term outcome will be development of an anti-infective vaccine against HME in humans that does not cause adverse effects.

过去二十年里，蜱传疾病的发病率急剧上升，并且还在继续上升。由恰菲埃利希体 (Ech) 引起的人类单核细胞埃利希体病是最流行的生命性疾病之一。美国新出现的威胁性蜱传人畜共患病。 Ech 是一种必需的细胞内细菌立克次体目。选择的治疗方法是广谱抗生素强力霉素，只有开始使用才有效早期的。目前尚无 FDA 批准的埃希疫苗。我们的长期目标是开发一个证据- 基于立克次体的多个关键步骤来有效保护人类的疫苗方法感染周期。为了实现这一目标，我们鉴定了四种具有已知功能的 Ech 表面暴露蛋白 Ech 生存所需，并且与人类蛋白质 OMP-1/P28、进入触发蛋白缺乏同源性埃利希体 (EtpE) 和 VirB2。 OMP-1/P28 是免疫显性表面暴露的外膜蛋白具有细菌获取营养所必需的孔蛋白活性。 P28 和 OMP-1B 主要是分别在哺乳动物和蜱中表达。 EtpE 是一种侵袭素，利用其 C 末端 (EtpE-C) 结合宿主细胞受体触发 Ech 进入。我们已经证明 IV 型分泌系统（T4SS）对于 Ech在宿主细胞内存活。 VirB2 是一种 T4SS 菌毛蛋白，是 T4SS 机制的一部分。免疫接种具有重组 P28、EtpE 或 VirB2 蛋白的小鼠产生 Ech 特异性抗体反应，预防了 Ech 感染。这些数据支持我们的假设，即这些蛋白质可作为合理的疫苗靶向哺乳动物宿主细胞 Ech 感染中非重叠过程的候选者。 DNA疫苗与传统疫苗相比，它具有许多潜在优势，包括刺激体液和 T 细胞介导的反应、提高的疫苗稳定性、不存在任何感染因子以及相对易于包装多部件和大规模制造。我们展示了 Ech DNA 的可行性通过经皮无针喷射注射对狗进行 DNA 疫苗安全免疫，从而对狗进行疫苗接种并展示对 DNA 疫苗的体液和细胞介导的免疫反应。我们的假设是使用单独或组合编码 P28、OMP-1B、EtpE 和 VirB2 的质粒 DNA 疫苗进行免疫防止 Ech 从蜱传播到哺乳动物。为了检验这一假设，我们的具体目标是： 1. 构建编码 P28、OMP-1B、EtpE-C 和 VirB2 的 DNA 疫苗，确定体液发育和免疫小鼠中细胞介导的免疫反应，并评估免疫小鼠的保护作用感染蜱细胞中培养的 Ech。 2.测试犬是否接种P28、OMP-1B、EtpE-C和VirB2 可以防止受感染蜱传播 Ech。拟议研究的直接结果将是为用于阻断 Ech 的 Ech 候选疫苗的 DNA 疫苗方法提供原理验证从蜱虫传染给狗。长期成果将是抗感染疫苗的开发对抗人类的 HME，不会造成不良影响。