Targeted Prevention of Human Ehrlichiosis

人类埃利希体病的针对性预防

• 批准号: 10470709
• 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
• 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/10470709
• 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

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.

在过去的二十年中，tick传播疾病的发病率急剧上升，并继续上升。 由埃里希亚（Ehrlichia chaffeensis）（ECH）引起的人类单核细胞性卵形病是最普遍的生活之一 威胁性的，在美国新兴的tick传说。 ECH是阶的强制性细胞细菌 立克西亚斯。选择的治疗是广谱抗生素强力霉素，这仅在启动时有效 早期的。当前没有FDA批准的ECH疫苗。我们的长期目标是建立证据 - 基于疫苗的方法，通过针对立克的多个关键步骤有效保护人类 感染周期。为了实现这一目标，我们确定了四个具有已知功能的ECH表面暴露蛋白 ECH生存所必需的，并且还缺乏与人蛋白的同源性OMP-1/P28，进入蛋白 ehrlichia（ETPE）和VirB2的作品。 OMP-1/p28是免疫主​​导表面暴露的外膜蛋白 对细菌营养的获取至关重要的孔蛋白活性。 P28和OMP-1B主要是 分别用哺乳动物和壁虱表达。 ETPE是一种使用其C末端（ETPE-C）结合的入侵蛋白 宿主细胞受体触发ECH进入。我们已经表明，IV型分泌系统（T4SS）对于 宿主细胞内的ECH生存。 ViRB2是T4SS pilus蛋白，是T4SS机械的一部分。免疫 具有重组P28，ETPE或VIRB2蛋白的小鼠产生ECH特异性抗体反应的小鼠 防止了ECH感染。这些数据支持我们的前提，即这些蛋白质是理性疫苗 靶向哺乳动物宿主细胞ECH感染中非重叠过程的候选。 DNA疫苗 与传统疫苗相比，提供许多潜在的优势，包括刺激体液和 T细胞介导的反应，改善的疫苗稳定性，没有任何感染剂以及相对 易于包装多组件和大规模制造。我们展示了ECH DNA的可行性 通过无针喷射，通过DNA疫苗安全免疫狗，狗中的疫苗 并证明对DNA疫苗的体液和细胞介导的免疫反应。我们的假设是 用编码P28，OMP-1B，ETPE和VIRB2的质粒DNA疫苗进行免疫接种或组合 防止ECH从壁虱传播到哺乳动物。为了检验这一假设，我们的具体目的是：1。 构造编码P28，OMP-1B，ETPE-C和VIRB2的DNA疫苗确定体液的发展 免疫小鼠中细胞介导的免疫反应，并评估免疫小鼠免疫反应 在tick细胞中培养的ECH感染。 2。测试P28，OMP-1B，ETPE-C和VIRB2的狗是否免疫 可以防止ECH传播受感染的壁虱。拟议研究的直接结果将是 提供原则证明DNA疫苗方法的ECH疫苗候选物，以阻止ECH 从壁虱传播到狗。长期结果将开发抗感染疫苗 反对人类中不会造成不利影响的人。